JJG 640-1994 Verification Procedure for Differential Pressure Flowmeter JJG640-1994 Standard download decompression password: www.bzxz.net
This procedure is applicable to the verification of newly manufactured, in-use and repaired differential pressure flowmeters. Differential pressure flowmeters such as averaging tubes, wedge-shaped flow sensors and elbow flowmeters should also be verified according to this procedure.

Differential pressure flowmeter calibration procedure
JJG 640—-1994
Good pressure flowmeter calibration procedure
YericatlnReuulationof
Difrerential Pressur: 'Type
Fitwmeter
JJG1 (40—-1994
代许2(7—1982
I'G311 -1583 :
271184 7
TG 621-15x5
11G —1591
This verification procedure was approved by the National Technical Committee on July 12, 194, and was implemented from 12H0FH onwards. The responsible unit is: Beijing Municipal Bureau of Technology
The drafting unit: Beijing Institute of Science and Technology of China This procedure is based on the drafting of the technical documents and is responsible for interpreting the principles of this regulation. The main drafters are:
Xiu Zi (China Institute of Metrology)
Xie Ji Lan [Beijing Institute of Measurement and Testing)
Yang Xiwen [Beijing Institute of Metrology)
Participating drafters:
Peng Xia Qin [Shanghai Institute of Industrial Automation and Instrumentation]
President (Beijing Institute of Measurement and Testing)||t t||Zhang Jixing (Hutou City Instrument Factory)
Han Qingchang (Galaxy Instrument)bzxz.net
Yu Zhilin (Dalian Xiangong Instrument)
Technical requirements
) Quick verification
(ii) Coefficient verification -
(a) Pressure gauge or differential pressure transmitter
Verification items
Geometric method
(ii) Coefficient verification
(a) Pressure gauge or differential pressure transmitter
Verification items verification method
(a) What kind of inspection method.
a) Coefficient verification -
:) Differential pressure gauge or differential pressure transmitter
V. Verification result processing and verification cycle
Appendix?
Appendix 3
The installation method of differential pressure signal pipeline and the main parameters of the original throttling device
Equivalent absolute roughness K value of the wall
Medical record 4
Measurement method of hole sharpness
Criteria for removing large and large errors
Appendix Estimation of fluid density
Appendix 7 Verification items and design of differential pressure gauge Appendix 8 Inspection and verification format before the back of the book Appendix! Calculation method format of throttling device
Verification procedures for differential pressure flowmeter
This procedure is applicable to new manufacturing. The differential flowmeter should be used in accordance with the actual situation: for the average speed intelligent, shaped flow sensor and bend throttling Zhu and other wild pressure gradual flowmeters, the control technology specification should also be calibrated. Overview
1 Composition
Differential flowmeter is sufficient to allow the throttling device [differential flow transmitter (hereinafter referred to as the complete sensor): and differential pressure meter or differential pressure transmitter and display instrument (hereinafter referred to as the simple differential pressure meter) 1 Two parts:, the small signal pipeline between the left and right mountain coupons (its installation principles see 1) Press: The composition diagram of the differential flowmeter 1, the throttling device
left and right
melt state 1. The differential flow control device includes throttling parts, joint installation and front and rear measuring belts, apte. The throttling parts included in this specification include standard orifice plate, standard nozzle, long diameter nozzle, classic venturi tube, venturi nozzle, and paved inlet hole, 1/4 nitrogen hole, sieve hole, embedded orifice plate, 2. The differential flow control device is sufficient to prevent the flow of the throttling parts from flowing through the throttling parts [transmitter], and the pressure is proportional to the breeze. 3. Inspection 3.1 Geometric inspection method The inspection of the throttling parts, quality devices and downstream general construction should be included. 3.2 Coefficient verification includes the following contents: balancing tubes, shape sensors and control tubes, etc. 3.2.1 Throttle devices that fail to meet the test requirements and cannot be corrected by the test method; 3.2.3 Throttle devices that are not suitable for use; 3.2.4 Throttle devices that are controversial during use and must be verified; 3.2.5 Other types of intelligent devices or sensors, 3.3 Differential pressure gauges This regulation includes differential pressure gauges with measurement principles such as position balance (e.g. double wave mosquito tube differential pressure gauge): square intercept type (e.g. -〖, neutralization micro-shift (e.g. capacitance type, etc.), etc. The main symbols of this regulation are listed in Table 1, and the other symbols can be seen in the relevant instructions. Table 1 will be the measurement coefficient a - C:. 1 -
conditions, art hole (or cause drop through]
working parts, on both sides also road diameter (or need device) effective time stick degree
ice accumulation in the most
several plates force read five nearly half certificate
agricultural surface Shanghe has a learning purchase
and the spray diameter beauty of the breeding effect
on the body to release
necessary effectiveness extension degree
fluid movement analysis seat: =
: quantity (difference 1
! (sense) of non-standard degree
possible ability of its stimulation of non-material second launch
ML.-..T-1
L2-T 1
Throttling bucket (or sensor) single and equal internal and external hardness not two show library throttling for light (limited to white) uncertain stop you not sure what
quality not with is
company: [. Indicates length; M together with water quality: Ding a change time technical requirements
(--) any inspection method
Marking and random documents
5.1 Marking
Throttling device must call the obvious part of the sensor should have the direction mark, also should have the nameplate, the nameplate will indicate the manufacturer name; product name and type pregnancy, to the date of the movement number: valley source diameter; working pressure; liquid hole diameter. 5.2 Tunnel machine documents
Throttling device The stomach and the sensor should have no calculation book and trial instructions. The throttling parts only take the history. The shape of the soft plate is shown in Figure 2. The pressure of the hole is taken by angle. The flange pressure and the flatness of the upstream end should be less than 0.5%. 6.1.21 The roughness of the whole end face A and the shape of the Wanli Feijian mail meet the requirements of the road group. 6.2 Plate-shaped inlet orifice plate
6,1,3 Edge, H and [
Upstream edge has no curling and seven thorns and no visible defects:
, the edge is sharp and the total length is not more than 0.0004d:
Downstream edge H and "are not allowed to have obvious pressure defects, .1.4 Di and back-shaped length
between (0.005-0.02), the difference between the values ​​at any position shall not exceed -0001
b, and the degree of enjoyment is -0 ,U5D when = [m
, the above can be equal to 3.2m: the difference between the values ​​measured at any inspection position shall not exceed .001"
6.1.5 Flow diameter d
n.t12.5m:
h. The difference between a diameter and the average diameter is not large. The average diameter of the working point diameter is 3.05
6.1.6 The bevel angle of the mountain mouth is small. The bevel angle is between (3-, the shape of the 1-dimensional orifice plate is shown in Figure 3, which adopts angle connection to suppress elimination. 6.2.1 The flatness of the plane of the A surface
A and the flatness should be less than I%, and there should be no local defects within the range of F.5&, and the surface roughness R
of the f.1.24 surface 1.5 should meet R3×10-, and the R of the population head chain part 1 and the direction should also meet the above requirements.
6.2.3 The bevel angle of the population
should be between (44.-46)\:
6.2. The sum of thickness, F and length 1, should be
2F:: 0.105
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