250/2001 Coll.
DECREE
Ministry of Industry and Trade
Dated 22 June 2001
Laying down the requirements for the belt weigher called
EEC mark
Change: 260/2003 Coll.
Ministry of Industry and Trade, pursuant to § 27 of Law no. 505/1990
Coll., On metrology, as amended by Act no. 119/2000 Coll., (Hereinafter the "Act") to implement §
6 paragraph. 2 and § 9 par. 1 of the Act:
§ 1
This Decree lays down the requirements for the belt weigher, which
are automatic weighing machines which determine the mass of the products freely
bulk without systematic subdivision, the movement of the belt is
smooth, and the description is given in Annex hereto.
§ 2
Belt weighers can be used instead of official marks
established by special legislation 1)
bear the EEC approval and EEC initial verification, the graphic appearance
by special legislation, ^ 2) only if
meet the requirements set out in the Annex hereto, which have been verified
procedures laid down by special legislation. ^ 2)
§ 3
This Decree shall take effect on the date of publication of the Sectoral Annex for
meter to the Protocol to the Europe Agreement establishing an association between
Czech Republic on the one hand and the European Communities and their Member States
the other, on Conformity Assessment and Acceptance
industrial products in the Collection of international Treaties, or the date of entry
treaty of accession of the Czech Republic to the European Union enters into force, will
if this date is earlier.
Minister
:
Doc. Ing. Grégr vr
Arrival.
Belt weighers first Classification of weighing devices according to the method of their
traffic
1.1 Automatic weighing equipment
Machines accomplishing a weighing operation without operator intervention
and setting in motion an automatic process
characteristic of the machine.
1.2 Non-automatic machines
Devices that require operator intervention during the process
weighing, especially to deposit or remove the loads from the carrier
loading machine and also to determine the result.
Second terminology
2.1 General
On the belt weighers are subject to the requirements of section
1 and 2 of Annex no. 1 special legal
prescription ^ 3), unless this Decree stipulates otherwise.
2.2 Classification
2.2.1 According to the method of determining the amount
2.2.1.1 Census belt weighers:
Belt weighers on which the totalizing device
successively incremented after successive partial load
each of which corresponds to a given distance traveled
belt.
2.2.1.2 Integration belt weighers:
Belt weighers on which the totalizing device
performs the integration product of the load belt
and the belt speed by time.
2.2.2 Depending on the load carrier
2.2.2.1 Belt weigher with weigh table:
Belt weighers on which the load carrier
called the "weigh table" are only a part
belt conveyor.
2.2.2.2 Belt weigher with conveyor:
Belt weighers on which the entire belt
conveyor weighing bridge.
2.3 Parts of the belt weigher
2.3.1 Main parts
2.3.1.1 Conveyor
Device intended for conveying the product by means of a belt
deposited on rollers turning about their axes.
2.3.1.1.1 support rollers
War, through which the conveyor belt is supported in
fixed frame.
2.3.1.1.2 Weighing war
Cylinder, by means of which conveyor belt is
on the load weighing unit.
2.3.1.2 Weighing unit
The entire non-automatic weighing equipment or a part thereof or
any other device providing information on
the weight of the load.
2.3.1.3 Belt displacement transducer
Device on the conveyor supplying either
information corresponding to the displacement of a defined length of the belt or
information proportional to the speed of the belt.
2.3.1.3.1 Displacement sensing conveyor belt
That part of the displacement sensing device that is permanently
associated with the belt.
2.3.1.4 solver
Equipment performing partial loads or
integration of the product of the load and speed of the belt
Belt according to time on the basis of information supplied by the weighing
unit and the displacement transducer conveyor belt.
2.3.1.5 Indicator computing equipment (totalization)
Device receiving information from the totalization device and
indicating the mass conveyed.
2.3.1.5.1 amount counter without reset devices (totalising counter
)
Counter indicating the overall total weight of all
conveyed.
2.3.1.5.2 counter with zero-resetting device
Counter number of products transported for certain
limited period of time.
2.3.1.5.3 Additional counter amount
Counter with a scale interval greater than
The value of sum counter, intended to indicate
total weight of products transported over longer
time. This device may be equipped with zeroing
device.
2.3.1.5.4 Inspection counter
Device with a smaller scale interval than the value of the interval
capital sum counter, designed to control
purposes.
2.3.1.6 Reset device
Device by which the belt weigher is set to
zero when running idle belt at the time of its full
circulation;
Zero-setting device may be either non-automatic,
semi-automatic or automatic.
2.3.1.6.1 indicating device for zero setting (zero
indicator)
Additional counter amount corresponding to the reset
devices which can check the zero setting
the belt weigher at idle treadmill.
2.3.1.6.2 Non-automatic zero-setting device
Device allowing observation, setting and
checking the zero setting belt
weights operator.
2.3.1.6.3 Semi-automatic zero facilities:
a) allows for manual command automatic zero adjustment
belt weigher
b) the device indicating a manual command value needed
adjustment balances to zero.
2.3.1.6.4 Automatic reset device
Device enabling zero-setting belt
conveyor belt scales when running idle without intervention
operator.
2.3.2 Attachments
2.3.2.1 device for indicating the instantaneous load
Device indicating the mass of the load acting on the weighing
unit at any given moment.
2.3.2.2 device for indicating flowrate
Device indicating the instantaneous flowrate either as
the weight of the product conveyed in unit time or
as a percentage of the maximum flowrate.
2.3.2.3 checking device functions
Device allowing control of certain functions especially
via:
- Simulating the effect of a constant load with the belt empty
(Devices for monitoring during idling with additional weight
)
- Compare two integrations device for constant
same time interval
- Indication of the maximum load or maximum
flowrate
- Alert the user to mistake activity tracked
weigher and in particular in the electrical equipment.
2.3.2.4 Device for regulating the flowrate
Device intended to ensure a programmed flowrate
performance.
2.3.2.5 Equipment preset amount
Equipment to stopping feed to
conveyor when the totalized load
reached a preselected value.
2.3.2.6 of the displacement simulator
Auxiliary equipment used in tests on the belt
weigher without its conveyor and intended to
simulate displacement of the belt.
Third Metrological characteristics
3.1 Totalization scale interval
Value, expressed in units of mass that
equals:
- In the case of continuous (analogue) indication the
the smallest scale interval counter quantities (dt)
- In the case of discontinuous (digital) indication, the difference
between two consecutive figures
Counter amount (dtd).
3.2 The value of (D0) zero indicator
The value of (D0) zero indicator expressed in
units of mass, equals:
- In the case of continuous (analogue) indication the
increments zero indicator
- In the case of discontinuous (digital) indication, the difference
between two consecutive figures
zero indicator.
3.3 weigh length (L)
The distance between the axes of the weighing rollers at the extremities
points weigh increased by the half distance
between the axes of each of these rollers and the axes closest
the supporting rollers of the conveyor and weighing
bridge.
3.4 Weighing cycle
Group of operations relating to each loading
load at the end of all the parts of the calculation
first device returns to its initial position or state.
3.5 Maximum capacity (Max) and minimum capacity (min)
Weighing units
3.5.1 The maximum capacity
Maximum instantaneous net load on the conveyor belt
for which the weighting is determined by weighing unit.
3.5.2 Minimum capacity
Value of the net load below which the use
weighing results may cause an excessive relative error in
totalization result.
3.5.3 Weighing range of the unit
Interval between the minimum and maximum capacities.
3.6 Maximum flowrate (Qmax) and the minimum flowrate
(Qmin)
3.6.1 Maximum flowrate
The maximum flowrate obtained with the maximum capacity
the weighing unit and the maximum speed of the belt.
3.6.2 Minimum flowrate
Value of the flowrate below which the results can be
Weighing subject to excessive relative errors.
3.7 Average test flowrate (QE)
Quotient of the totalized mass (C) and the duration of the test (t)
C
Qe = ------
t
3.8 Minimum totalized load
Minimum totalized mass of a product below which can be
the result affected by errors greater than the maximum
permissible errors for any flowrate between
maximum and minimum values.
3.9 Maximum linear load belt
Fraction of the maximum capacity of the weighing units and weighing
length:
Max
-------
L
Fourth Definition of accuracy classes
4.1 Accuracy classes
Belt weighers are divided into two classes
Accuracy:
Class 1
Class 2
4.2 Classification The
Belt weighers shall be classified according to their
metrological characteristics and qualities.
4.2.1 Characteristics of belt weighers Class 1
4.2.1.1 Totalization scale interval:
Totalization scale interval shall be:
1
- Less than or equal ------- weighed amount per
2000
one hour at maximum flowrate,
1
- Greater than or equal to that quantity -------
50000
4.2.1.2 The scale interval of the zero indicator (D0)
Without exceeding the totalization scale intervals
must be:
- The value of continuous (analogue) scale smaller
1
than or equal to the quantity of weighed -------- per
20000
hour at maximum flowrate,
- The value of discontinuous (digital) scale
1
-------- less than or equal to this amount.
40000
4.2.2 Characteristics of belt weighers Class 2
4.2.2.1 Totalization scale interval:
Totalization scale interval shall be:
1
- Less than or equal ------- weighed quantity per
1000
hour at maximum flowrate,
1
- Greater than or equal -------- this quantity.
25000
4.2.2.2 The scale interval of the zero indicator:
Without exceeding the totalization scale intervals
must be:
- The value of continuous (analogue) scale smaller
1
or equal -------- quantities weighed per
10000
hour at maximum flowrate,
- The value of discontinuous (digital) scale
1
must be less than or equal --------- this amount.
20000
4.2.3 The scale intervals
The subdivisions must answer:
1.10n, 2.10n, 5.10n, n is a positive or negative whole
number or zero;
The subdivisions zero indicator and control
indicator need not comply with this requirement.
4.2.4 Belt weighers checking device
idle with additional mass
The conditions set out in paragraphs 4.2.1.2, 4.2.2.2 and 4.2.3
relating to the zero indicator is also valid for
Indicators of control values.
4.2.5 Minimum flowrate
The minimum flowrate shall be 20% of the maximum
flowrate.
Fifth Maximum permissible errors
Belt weighers which are at idle
correctly to zero, for any totalized amount
greater than or equal to the minimum totalized load below
maximum permissible positive or negative errors.
5.1 Maximum permissible errors on initial verification EEC
5.1.1 Class 1
0.5% of the totalized load for any flowrate between 20 and
100% of the maximum flowrate.
5.1.2 Class 2
1% of the totalized load for any flowrate between 20 and 100%
maximum flowrate.
5.2 Maximum permissible errors in service
5.2.1 Class 1
1% of the totalized load for any flowrate between 20 and 100%
maximum flowrate.
5.2.2 Class 2
2% of the totalized load for any flowrate between 20 and 100%
maximum flowrate.
6th Applicability of the maximum permissible errors
6.1 Indicating device digital
If the control device indicating discontinuous
(Digital), the maximum permissible errors magnified
on one scale interval of this device.
6.2 Indicating devices in multiple
Where a belt weigher is fitted
several counters quantity, the errors result
none of them exceed the maximum permissible error.
The difference between the results of weighing at the same
weighed amount of product must be less than or equal to:
- One scale interval of the discontinuous (digital)
indicator, where the results are supplied by two
discontinuous (digital) indicators
- Absolute value of the maximum permissible error if they are
the results are supplied by two continuous (analogue)
indicators;
- The larger of the two values:
- Absolute value of the maximum permissible error, or
- One scale interval of the discontinuous (digital)
scale
when the results are supplied by a continuous
(Analogue) indicator and a discontinuous one
(Digital) indicator.
6.3 Simulation tests
6.3.1 The maximum permissible positive or negative errors in
Simulation tests
6.3.1.1 Class 1:
for any flowrate between 5 and 20% of the maximum
flowrate:
0.07% of the load totalized at the maximum flowrate
the duration of the test;
for any flowrate between 20 and 100% of the maximum
flowrate:
0.35% of the totalized load.
6.3.1.2 Class 2:
for any flowrate between 5 and 20% of the maximum
flowrate:
0.14% of the load totalized at the maximum flowrate
the duration of the test;
for any flowrate between 20 and 100% of the maximum
flowrate:
0.7% of the totalized load.
6.3.2 Equipment for simulate displacement of the belt
When simulating the feed rate required for
testing, the relative simulation error
exceed 20% of the maximum permissible error for the totalized
load.
This error is included in the maximum permissible
errors.
6.3.3 The difference between the two results obtained due to a variation
Simulated speed
At each change of the speed of the displacement simulator,
corresponding change to + - 10% of the velocity of the belt
Conveyor specified by the manufacturer, not the relative difference
Error results of simulation tests exceed 20%
the maximum permissible errors specified in paragraph 6.3.1.
6.3.4 The difference between the two results obtained by varying the place
imposing burdens as well
When changes instead of saving the same way load
compatible with the design weigh not be
the difference between the two results is greater than the absolute value
the maximum permissible error.
6.3.5 Setting zero
For every load that can be set to at
zero balance, the weighing results reset
belt scales meet conditions for
the maximum permissible error for the totalized load.
6.3.6 Influencing factors
6.3.6.1 Temperature
Belt weighers must comply with the following reset
requirements relating to the maximum permissible errors
when all the actual constant temperatures between -10 and
+40 St. C. For special applications, however, may have the following
belt weighers different temperature ranges from those
above. In this case, the interval must be
at least 30 st. C and must be indicated on the label
nominals. During the tests are considered
temperature constant if the variation is more than
5 st. Course.
A change of 10 Wed C, and if the temperature change is greater
than 5 st. C / hour, not zero indication, or in the case
belt weighers checking device
idle with additional mass, the control value
belt weigher differ by more than:
0.07% for Class 1
0.14% for Class 2
load totalized at the maximum flowrate for
the duration of the test.
6.3.6.2 Influence of power supply
Belt weighers must complement requirements
relating to the maximum permissible errors without
intermediate setting to zero, within the following limits
fluctuation of power supply:
- From -15 to + 10% of nominal voltage,
- From -2 to + 2% of the nominal frequency.
6.3.6.3 Other factors affecting
Under normal conditions of use, the belt
scales meet the requirements relating to the maximum
permissible errors when they are exposed to the other
influencing factors than those referred to in paragraphs 6.3.6.1 and
6.3.6.2 and resulting from the conditions of their installation
(Vibrations, atmospheric conditions etc.).
Metrological characteristics 6.3.7
6.3.7.1 Repeatability
The difference between the results of weighing obtained a
same load placed under the same conditions on the weighing
bridge, must not be greater than the absolute value of the maximum
permissible error.
6.3.7.2 Resolution computing equipment
For any flowrate between the minimum and maximum
flowrates and for two loads differing from each other by
value equal to the maximum permissible error for
the burden must be equal to the difference between the results
at least one half of the calculated value corresponding
difference between these loads.
6.3.7.3 Resolution zero indicator:
for tests lasting three minutes must be clearly
visible difference between the results obtained at no load and
a load deposited or removed, equal to the following
percentages of the maximum capacity:
0.1% for Class 1
0.2 class 2.
6.3.7.4 Zero stability
6.3.7.4.1 short-term stability
The difference between the smallest and largest results
obtained after five tests of three minutes idling
shall not exceed the following percentages of the load
totalized in one hour at maximum flowrate
Performance:
0.0025% for Class 1
0.005% for Class 2.
6.3.7.4.2 Long-term stability
The tests described in paragraph 6.3.7.4.1 must be repeated after
three hours of idle under stable test
conditions and without continuous resetting:
- The difference between the smallest and largest results obtained
Weighing shall not exceed the limits set out in paragraph 6.3.7.4.1,
- The difference between the smallest and largest of all
weighing the results obtained (in paragraph 6.3.7.4.1 and the first indent of this paragraph
) may be greater than
The following percentages of the load totalized in
one hour at the maximum flowrate:
0.0035% for Class 1
0.007% for Class 2.
6.3.7.5 The additional amount counter
Additional computational devices:
- May affect the operation of the instrument,
- Must be constructed in a manner that ensures correct
results.
6.3.7.6 Belt weighers fitted with a device to control
idle with additional mass:
for belt weighers fitted for running
idle with additional mass, the provisions
set out in paragraphs 6.3.7.3 and 6.3.7.4 shall apply to testing with
additional mass; the maximum permissible deviations from
control value shall be calculated according to the following
provision.
6.4 Tests at the point of use
The maximum permissible errors shall be applicable to any quantity
product, which is at least equal to the minimum totalized
load.
6.4.1 Belt displacement transducer
There must be no slippage between the sensor and the belt.
6.4.2 Test equipment
The equipment used for testing weights with the product or
products intended to be weighed on the belt
scales for checking totalized load error
not exceeding 20% of the maximum permissible error.
6.4.3 The minimum totalized load
The minimum totalized load shall be at least equal to the largest
the following values:
- The load obtained at maximum flowrate in one
circulation belt
- 2% of the load totalized in one hour at the maximum
flowrate or 200 totalization scale intervals
for Class 1
- 1% of the load totalized in one hour at the maximum
flowrate or 100 totalization scale intervals
amount for Class 2.
Metrological characteristics 6.4.4
6.4.4.1 Differences between the relative errors:
The difference between the relative errors for several results
weighing obtained at virtually identical flowrates
at approximately the same quantities of products from
the same conditions, shall not exceed an absolute value
the maximum permissible error.
6.4.4.2 The maximum permissible errors in the zero
Zero indicator shall not after the whole number of revolutions
Belt exceed the following percentages of the load
totalized at maximum flowrate for the duration
test:
0.1% for Class 1
0.2% for Class 2.
6.4.4.3 Resolution zero indicator
In the tests corresponding to a whole number of revolutions
of the belt does not exceed three minutes, must be
clearly visible difference between the results obtained for
no load and the result obtained for a load deposited or
Removing and this difference must be equal to the following
percentages of the maximum capacity:
0.1% for Class 1
0.2% for Class 2.
6.4.4.4 Zero stability
After five tests corresponding to a whole number of revolutions
band for the duration as close as three minutes can not
the difference between the smallest and largest results obtained
Weighing exceed the following percentages of the load
in one hour at the maximum flowrate:
0.0035% for Class 1
0.007% for Class 2.
6.4.4.5 Belt weighers fitted with a device to control
idle with additional mass
For belt weighers fitted the
zero checking with additional mass, the
provisions set out in paragraphs 6.4.4.2, 6.4.4.3 and 6.4.4.4
also apply to testing with an additional mass;
the maximum permissible variations in the value shall be calculated
under these provisions;
Belt weighers fitted with a device to control
idle with an additional mass corresponding to 20%
Maximum capacity of the weighing unit, shall also comply
provisions on the checking of zero in paragraph 6.4.4.2.
Table 6.5 Overview of main metrological requirements
----------------------------------------------- -------------------------------------------------- -----------------------
Class 1 Class 2 -------------------------------------------
-------------------------------------------------- ---------------------------
The value of the counter Cmax Cmax Cmax Cmax
quantity (dt or dtd) (point - -------- <dt = dtd or <= -------- -------- <dt = dtd or <= ---------- || | 4.2) 50000 2000 25000 1000
---------------------------------------- -------------------------------------------------- ------------------------------
scale interval Cmax Cmax
zero indicator (to) Continuous indication to < = --------- Continuous indication to <= ----------
(4.2) 20,000 10,000
Cmax Cmax
Discontinuous indication to <= ---------- discontinuous indication to <= ----------
40000 20000
and <= dt or dtd and <= dt or dtd
--------------------------------- -------------------------------------------------- -------------------------------------
maximum permissible errors (tests VAZ .produktem)
- initial verification (5.1)% 0.5% C C 1
- operating (section 5.2) 1% 2% C C
--------- -------------------------------------------------- -------------------------------------------------- -----------
Usability maximum permissible errors (see section 6)
simulation testing (section 6.3)
------------ -------------------------------------------------- -------------------------------------------------- --------
maximum permissible errors (section 6.3.1)
- for Qmax / 20 <= Q <= Qmax / 5 Qmax xt 0.07% 0.14% Qmax xt
- for Qmax / 5 <= Q <= Qmax 0.35% C 0.7% C
--------------------- -------------------------------------------------- ------------------------------------------------- | || temperature (section 6.3.6.1)
the deviation in the zero indication at Qmax xt 0.07% 0.14% Qmax xt
temperature change of 10 Wed C
---------------------------------------------- -------------------------------------------------- ------------------------ Resolution
zero indicator (section 6.3.7.3) the difference between the results obtained at no load and the load || | -------------------------------------------------- ----------------------------------------
0.1% up to 0.2% max
-------------------------------------------------- ----------------------------------------
It must be easily recognizable -------------------------------------------
-------------------------------------------------- ---------------------------
zero stability (section 6.3.7.4) For tests lasting three minutes
- short-term stability, deviation <= 0.0025% C max deviation <= 0.005% Cmax
- term stability deviation <= 0.0035% C max deviation <= O, 007% Cmax
----------- -------------------------------------------------- -------------------------------------------------- ---------
tests on site
(section 6.4) ------------------------
-------------------------------------------------- ----------------------------------------------
Value minimum totalized> = 1 circulation belt at Qmax> = 1 circulation belt at Qmax
load (section 6.4.3)> = 2% Cmax> = 1% Cmax
> = 200 or dtd dt> dt = 100 or dtd
----------------------------------- -------------------------------------------------- -----------------------------------
resolution null indicator of difference between the results of tests obtained unloaded and load:
(section 6.4.4.3) --------------------------------------- -------------------------------------------------- -
0.1% up to 0.2% max
-------------------------------------------------- ----------------------------------------
Must be clearly distinguishable -------------------------------------------
-------------------------------------------------- ---------------------------
zero Stability (section 6.4.4.4): For the tests in duration approaching about as much as possible three minutes and
corresponding to a whole number of revolutions of the belt
------------------------------------------ -------------------------------------------------- ----------------------------
- stability (short term) deviation <= 0.0035% C max deviation <= 0.007% Cmax
----------------------------------------------- -------------------------------------------------- -----------------------
C = totalized load.
T = test duration in hours.
Cmax = load totalized in one hour at maximum flowrate
performance.
7th arrangement
Belt weighers must include:
- Conveyor belt,
- A weighing unit,
- Belt displacement transducer,
- Computational devices
- Counter which,
- Zero-setting device.
Zero setting device on belt
weights must be fitted with a zero indicator sum
counter, or a device for controlling idling with
additional mass, when:
- Counter which indicates only positive values, or
- The value of sum counter is greater than
The value of the zero indicator specified in paragraph
4.2.1.2 for Class 1 and paragraph 4.2.2.2 for Class 2.
7.1 Protection correct operation
7.1.1 Prohibition attributes to fraudulent use
Belt weighers must be designed so that
did not allow undue influence resulting data.
7.1.2 Impossibility of maladjustment or accidental breakdown
Both mechanical and electro-mechanical belt weighers must
It is so designed that it can not normally be
maladjustment or accidental breakdown without effect
maladjustment or the accidental breakdown being easily
detectable.
7.1.3 Protection of the controls of the belt weigher
Controls of the belt weighers must be
constructed so as to normally not
get into other positions than those structures
intended for them, so the handling is impossible
any indication or printing.
7.1.4 Counters amount placed separately from the belt
weigher must be provided with devices
complying with section 7.8
7.2 Belt conveyor
7.2.1 Belt weigher with conveyor:
The conveyor shall have robust construction and shall
to form a rigid assembly. When the roller support is used
as the only load lever of the weighing unit, it must
product to be stored on the pivot point of the lever.
7.2.2 Belt weigher with weigh table:
The skeleton of the conveyor must have a solid construction. In each
straight longitudinal section must be cylindrical path such that
belt is constantly supported on the weighing rollers, so that
It ensures proper weighting. The conveyor shall be
provided, if necessary, belt-cleaning device,
the position and operation must not affect the results.
7.2.3 Special installation conditions
Belt weighers shall be such that the installation
roller track, the composition and mounting of the belt and the arrangement
the supply of the product do not cause any errors in the result.
7.2.3.1 roller coaster
Where necessary, they must be effectively available
protection system against corrosion and clogging;
upper level of the rollers in the same group must be
practically in the same plane;
roller track shall be such as to prevent
slipping the article.
7.2.3.2 Conveyor belt
7.2.3.2.1 Linear weight belt
Linear weight belt must be constant; the connection may not
cause any disturbance activity.
7.2.3.2.2 speed and the length of the belt must be such that the zero setting
It can be done in a time not exceeding three minutes
however:
if it can not be met, this provision must be
Belt weighers fitted with semi-automatic or
automatic zero setting device.
7.2.3.2.3 speed of the belt shall not vary by more than 5% of the value
the speed at which the belt weigher
constructed.
7.2.3.3 weigh length
Belt weighers shall be constructed in such a way that
weigh length in operation remained
the same;
It must be possible to seal the setting elements of effective
weigh length.
7.2.3.4 Tension belt
Belt tension must be at a given point on the roller track
constant;
voltage must be such that under normal working
conditions does not slip between the belt and the driving
drum.
7.2.3.5 Effect of the product
Supply of the product on the conveyor must not affect
weighing results.
7.3 Weighing unit
7.3.1 General
The weighing unit shall be suitable for their purposes. Must
ensured, where necessary, against the effect
accidental loads greater than the maximum capacity.
Of the load must be designed so that it can not
cause additional errors whenever the feed.
7.3.2 load-balancing device
Load-balancing device shall have a continuous
from zero to a value of mass at least equal to the maximum
capacity. Weighing shall not commence until the weighing
unit is operating under normal working conditions.
7.4 displacement transducer belt
Belt displacement transducer (2.3.1.3.1) shall be designed
so, to avoid a slip which could affect
results, even when loaded or unloaded belt.
When the information is discontinuous it shall correspond stretch
strip which is equal to or less than the effective length
weigh.
When the information is continuous it must not be replaced by
independent of the conveyor belt except
checking or adjustment operations.
Amount of 7.5 counter
7.5.1 Quality indicator
Counter amount of printing devices
printing devices shall permit reliable, simple
and unambiguous reading of the results by simple
comparing the characters and must bear the name or mark the appropriate
Unit weight. Summing counter may not be possible
reset to zero.
7.5.2 Scale interval of belt weighers
with several totalization indicating a block
devices or without printing equipment.
The scale interval of the continuous (analog)
indicating device on the belt weigher not
exceed twice the scale interval of the discontinuous
(Digital) indication device. discontinuous
(Digital) indicating or printing devices on a belt weigher
must have the same scale interval.
7.5.3 Shapes weighing results at the discontinuous (digital)
indication
Results provided by discontinuous weighing
(Digital) indicating devices shall be shown
only in aligned figures.
7.5.4 Reliability weighing results
The indicated results can not be destroyed, for example
accidental stopping of the belt or power electrical
energy.
7.5.5 span
Counters must be made so that
allow the reading of a value at least equal
the quantity of product weighed in 10 hours of operation at
maximum flowrate.
7.5.6 Additional counters quantity
The scale interval of the supplementary counter quantity
must be at least equal to 10 times the interval sum
counters listed on the descriptive plate.
Requirements of section 4.2 are not applicable to these devices.
7.5.7 Connection counters quantity
Counters and printing devices or without
which only indicate positive values shall be disengaged
when the belt is operating unloaded.
Connecting and disconnecting computing devices must be
activated itself Belt weight due
belt load.
Counters and printing devices or without
which indicate positive and negative values shall be
engaged when the belt is operated unloaded and shall be
designed so that the indicated results can not
be affected by vibrations.
Inspection counter may be operated only during
test.
7.5.8 Control counter amount
Where the scale interval sum counter
greater than
- 0.1% of the minimum totalized load for Class 1
- 0.2% of the minimum totalized load for Class 2,
must be belt weighers fitted with a separate
control counter whose scale interval not exceeding
the above percentages.
7.6 Load for adjusting zero
It must be possible to balance the mass of the unloaded belt
acting on the load.
7.6.1 Non-automatic zero setting device
When adjusted manually, continuous
manner, then the linear resp. rotational movement of the adjusting
element of 10 mm or half a revolution per hour
must not exceed:
- 0.1% of the load totalized at maximum flowrate in
one hour for Class 1
- 0.2% of the load totalized at maximum flowrate in
one hour for Class 2.
When adjusted manually in a discontinuous
manner, not a single step adjustment in one hour their
effect exceed:
- 0.01% of the load totalized at maximum flowrate in
one hour for Class 1
- 0.02% of the load totalized at maximum flowrate in
one hour for Class 2.
It must be easily determinable whether any made
Correction positive or negative.
7.6.2 Semi-automatic or automatic device
adjusting zero
Semi-automatic or automatic device
Zero adjustment must be constructed in such a way
to:
- Setting to zero takes place after a whole number of revolutions
belt
- Has indicated the end of the activity,
- Were indicated limits of adjustments.
The error of adjustment of these devices in one hour of activity
must not exceed:
- 0.1% of the load totalized at maximum flowrate in
one hour for Class 1
- 0.2% of the load totalized at maximum flowrate in
one hour for Class 2.
Automatic zero-setting devices shall be during
Testing disconnected.
7.6.3 Equipment for controlling idling with additional
weight
Checking device works by using idle
additional mass, either placed on the weighing unit or
electrically simulated.
The device must meet the following requirements:
- The mass must be in a constant
in a manner appropriate mechanism
- The mass shall be possible only when the belt
revolving unloaded,
- The mass must be protected against dust
- The zero checking operation must always be carried
same way
- The zero checking operation must stop automatically after
predetermined whole number of revolutions of the belt
- At the end of the zero checking operation must be indicated
control value based on the additional mass and
number of turns of the belt.
7.6.4 Belt weighers checking device
idle with additional mass
Belt weighers fitted with totalization that
only indicate positive values shall be fitted
control equipment idle, according to paragraph 7.6.3.
The additional mass shall equal 5% of the maximum capacity
weighing unit.
Belt weighers fitted with totalization that
indicate positive and negative values may be fitted
a device for controlling idling, according to paragraph 8.6.3.
The additional mass must be equal to 5% or 20% of the maximum
capacity of the weighing unit.
7.7 indicating device for zero setting (zero indicator)
Indicating zero-setting device shall in no
case interfere with the results of the counter amounts.
7.8 Indication of failure maximum capacity of the weighing unit
or the maximum or minimum flowrates
If the value of the maximum flowrate or
capacity exceeded, or if it has not reached
value of the minimum flowrate must be given appropriate
signal.
7.9 Attachments
Ancillary devices must not affect the results.
7.10 Sealing
It must be possible to seal components of belt
weighers, the removal or adjustments
affect their metrological characteristics, in accordance with
conditions described in approval.
8th Labels are nominal values and labels for authentication
brand
Belt weighers must bear the following markings
in the order they are listed:
8.1 Compulsory basic data clearly expressed in the language of the country
determining
8.1.1 name or mark
8.1.2 name or symbol importer (for imported equipment)
8.1.3 Determining the belt weigher
8.1.4 Type and serial number of the belt weigher
8.1.5 Identification of products and for which the weights are determined
8.1.6 Minimum totalized load ......... kg or t
8.1.7 Number of cycles per hour (for belt weighers
working with adding one)
8.1.8 inscription: "Machine must be reset to zero at least every three hours
. Zero testing must take
least ..... revolutions" (The number of revolutions in the control setup is zero
given the EEC type approval according to paragraph 6.4.4.4).
8.2 Basic data expressed in code
8.2.1 In all cases mandatory: + - + + - +
- Mark EEC type 1 | | 2 |
- Indication of accuracy class in the form + - + or + - +
- The value of continuous (analogue) scale in
form dt =
- The value of discontinuous (digital) scale in
form dtd =
- Maximum capacity in the form Max .....
- Maximum flowrate in the form Qmax ....
- Minimum flowrate in the form Qmin ....
- Nominal speeds of the belt in the form v = .... m / s,
- Weigh length in the form L = .... m
- Identification mark on parts of the belt
weigher not directly connected with
main body.
8.2.2 Mandatory in certain cases:
- Scale interval of the indicating device
The zero setting shaped into =
- The control value with maximum possible variation is laid down in
Section 6.4.4.2 (for belt weighers
checking device with additional idle
weight).
8.3 Prefix
Depending on the particular use of the belt
weigher can be in the EEC type approval
Required metrological service issuing the certificate
EEC type approval, one or more additional markings.
Version 8.4 of identification and descriptive indication
Descriptive labeling and identification marks must be
indelible and have a size, shape and clarity,
which allow easy reading under the normal conditions
the use of the belt weigher.
They must be grouped together at one clearly visible
place the belt weigher on the label
fixed near the device
indication or inscribed directly on the indicator itself.
It must be possible to seal the plate bearing the markings.
8.5 Verification marks
The descriptive plate may include a space for
stamping. If this is not a face,
must be near the area available to
identified.
9th EEC type approval
EEC type approval of belt weighers must be
carried out in accordance with special legislation 2)
zpřesňujícími and the following additional requirements.
9.1 application for EEC type approval
Applications for EEC approval shall include the following
Information and documents:
9.1.1 The metrological characteristics
9.1.1.1 Nominal values according to section 8.
9.1.1.2 Special characteristics of the weighing unit.
9.1.2 Descriptive documents:
- Plan or sketch of the whole assembly,
- Any plans, or models or photographs
showing details of metrological interest,
- Description and schematic drawing showing clearly the operation
belt weigher.
9.2 Examination for EEC approval
Simulation testing 9.2.1
These tests must be carried on the belt
conveyor scales with the belt conveyor to which
to be connected or without it.
These tests must allow assessment of the impact
influencing factors which may affect the belt
weighers when used under normal conditions
(Temperature, voltage, frequency, etc.). Therefore it must
be examined separately.
The belt weighers must fulfill the requirements of
3.6
9.2.2 Tests under normal conditions of use
These tests include the weighted product in
an amount at least equal to the minimum totalized
load, at flowrates between the minimum
maximum values.
The belt weighers must fulfill the requirements of
4.6
10th EEC initial verification
EEC initial verification of belt weighers
carried out in two stages.
10.1 First stage:
- Checking that the belt weigher conforms
approved type and test various parts of their
mechanism
- Check counters quantities using the device
simulate displacement of the belt by points 6.3.1
6.3.3, 6.3.4, 6.3.5 and 6.3.7 except point 6.3.7.4.2.
For belt weighers with
conveyor (2.2.2.2), the tests shall be performed on
a complete machine.
For belt weighers with a weigh bridge
(2.2.2.1), the tests must be carried on the belt
conveyor weigher without the belt conveyor using
displacement simulation device of the conveyor belt.
These tests must show the result of totalization, ie. Totalized
mass and either the number of cycles or the number representing
Theoretically elapsed length of the belt for the duration of the test.
10.2 Second stage:
10.2.1 Tests at the point of use
It must be possible to carry out tests at the point of use and ease
reliable manner with the product or products that are
designed for weighing. Installation of belt weighers
It must be performed in such a manner that it can be
verification carried out without disrupting normal operations.
Test equipment meets the requirements of section 6.4.2 must
be permanently available in the vicinity of the belt
weighers to be verified and
storage and transport must be organized in such a
way as to avoid any loss of the
product.
10.2.2 Checking the displacement sensing device
If there is reason to suppose that may occur
slip displacement transducer, this must be slipping
measured.
10.2.3 Verify zero adjustment
This verification must be carried out over a whole number
belt revolutions under the conditions set out in paragraphs
6.4.4.2 and 6.4.4.5.
10.2.4 Zero stability
For tests in situ the stability of zero
satisfy the requirements of paragraph 6.4.4.4.
For devices connected to the checking device
idle with additional mass, the test shall be
carried out at least five times. The measured deviations from
control value shall not exceed the value calculated
according to the provisions of paragraph 6.4.4.4.
10.2.5 Tests with a weighted product
These tests shall cover under normal conditions of use
conduct at least two flowrates between
minimum and maximum values. They must be made with
amount of product equal to the minimum
totalized load.
Checking of the mass of the product shall
done before its passage over the belt
weights or after.
11th construction
Belt weighers which comply with the following
provisions shall be considered as complying with the relevant sections
previous chapters.
11.1 Special installation conditions
Belt weighers must comply with the following
installation conditions:
11.1.1 Roller track
The upper generatrices of the rollers and sets of rollers forming
conveying track must be in each group of rollers
parallel. Those that are located in the immediate
distance from the end of the drum, this does not necessarily
meet the requirement. The inclination of the axis extreme roller axes
central rollers shall not be greater than 20 st. for Class
1 and 30 st. class 2.
The inclination of the longitudinal section plane of the upper surface line
rollers shall not be greater than 10% for Class 1 and 20% for
Class 2 provided that it does not slip.
For Class 1, the weighing rollers and the carrying rollers,
situated immediately before and after the weigh bridge
mounted on ball bearings or on any
similar type of bearing; alignment of these rollers must be
load approximately equal to half the maximum capacity
such that the deviation in parallelism shall not exceed 0.3 mm
and the eccentricity error must not exceed 0.2 mm.
11.1.2 Conveyor belt
11.1.2.1 Connection portions of the belt
Belt shall consist of one or two parts, each having
the same characteristics; the connection must be oblique and the acute
angle between the joint and the lateral edge of the belt must
exceed 45 st.
11.1.2.2 Length
The length of the unwound belt shall not exceed the lesser of
following two values:
- The distance traveled by any point on the belt during 1.5
minutes at the lowest nominal speed,
- Or 100 m.
11.1.3 Effect of the product
The weighing platform must be placed from the feeding device
at a distance of between two and five times the distance
traveled by any point on the belt in one second at
maximum speed.
11.2 Belt displacement transducer
Measurement of the length corresponding to the displacement of the belt or measurement
rate must be made on the inner band portion.
For the integration of belt weighers must be
can provide the displacement sensor device for counting
revolutions or partial revolutions.
11.3 of the instantaneous load and flowrate
Parts of the scale of the instantaneous load and flowrate
performance corresponding to the values which do not lie between
minimum and maximum flowrates must be
differentiated from the rest of the scale.
These indicators may be replaced or supplemented
recording equipment, provided that it does not affect
results.
If the instantaneous load indicator is also
flowrate must bear the inscription:
"Flowrate valid for belt speed .... m / s."
11.4 Counter amount of printing or not printing
equipment
Counter amount and printing devices which indicate
Only positive values of the belt, must be connected at least
when the flowrate reaches 5% of its maximum value.
1) Decree no. 262/2000 Coll., Which provides uniformity and accuracy of measuring instruments and measurements
.
2) Decree no. 332/2000 Coll., That lays down some procedures
type approval and verification of measuring instruments known brand
EEC.
3) Decree no. 293/2000 Coll., Laying down technical requirements
NAWIs.
