GB/T 30040.2-2013Leak detection systems—Part 2: Pressure and vacuum systems (English PDF)

7.1 Overview

7.1.1 system of vacuum or pressure, including pressure changes caused by changes in temperature, should not exceed the tank, anti-seepage lining, leakproof Design parameters jacket or pipe. Among them, in accordance with Appendix A, under the conditions of pressure relief valve, the pressure can be more than double the gap allowed 90% of the maximum allowable pressure.

7.1.2 vacuum system vacuum pipe line leak detectors located and double gap between, each of which should be installed at a low condensate yield Collection device.

7.1.3 Leak detector system should be set calibration parameters (such as pressure switch threshold adjustment) and analog alarm system.

7.1.4 Leak communicating tube diameter and the gap between the double should be minimized.

a) the communication medium is air having an inner diameter of 6mm;

b) the communication medium is an inert gas having an inner diameter of 4mm.

7.1.5 Leak and double tank communicating pipe or double pipe between the gas flow when the flow rate of (85 ± 15) L/h, the total flow resistance should not exceed Too 1kPa. In the air as the media system, when the communication pipe length l is less than or equal to 50m, its inner diameter should be 6mm.

7.1.6 communication pipe leak detectors and double the gap between the labeling provisions should comply with the following colors.

--- Measuring tube. red;

--- Exhaust pipe or pressure pipe. white or colorless and transparent;

--- Exhaust pipe. green.

7.1.7 a vacuum leak can only be used a tank or a pipeline.

7.1.8 a pipeline can contain multiple duct portion, which double the gap should communicate with each section.

7.1.9 Leak in generating (85 ± 15) L/h gas flow rate should trigger an alarm, see Figure 1. Force change.

7.3 Vacuum leak detector

7.3.1 Overview

7.3.1.1 bilayer pressure should be maintained within the gap between subatmospheric negative pressure until a leak occurred before.

7.3.1.2 Vacuum leak detector for double flat tank should be able to withstand the expected pressure leak occurs.

7.3.1.3 alarm should ensure its reliability in accordance with 7.3.2, if not ensure, in conformity with GB/T 30040.4 double gap in most Low vacuum leak detector in addition to outside, and then install a liquid sensor.

7.3.2 Reliability alert

7.3.2.1 As a reliable guarantee, the vapor space should be double the gap increases leakage of the liquid is reduced, see equation (3).

100000Pa-pPA 100000Pa-p x 100% (3)

7.3.2.2 Preset alarm pressure pAE double gap is based on penetration of liquid

(leakage has occurred) compared to the lowest point of the tank has risen To h1, see formula (4). g x rhoP g x rhoG (4)

7.3.2.3 should be based on the geometry of the tank, calculate the gap in the double injection of liquid leakage when the height h1 volume (in liters or metering), See GB/T 30040.7.

7.3.2.4 if the following conditions are considered reliable alarms, see equation (5).

V < According to GB/T 30040.7.

A.2 Test device

Test device consists of the following components.

a) Pressure test vessel with a volume of 1L, at least two nozzles connected to a pressure pump and a pressure relief valve;

b) the environment (simulation) box, the temperature can range from -25 °C ~ 70 °C changes, accuracy 2K;

c) For the temperature range of -40 °C ~ 40 °C test, its environment (simulation) oven temperature range should be -50 °C ~ 40 °C, Accuracy 2K;

d) a pressure pump or air compressor;

e) servo control valves, pressure sensors and pressure programmable controller with an accuracy of 0.5% of the specified set pressure;

f) not more than two times the specified range set a pressure measuring device (for example. pressure gauge);

g) gas flow meter accuracy for the range (at least 300L/h) 1%; h) sink.

A.3 Ready

Pressure relief valve should be installed as shown in Figure A.1. Test vessel and pressure relief valve should be connected to the environment (simulation) box.

A.4 Assessment

A.4.1 Test valve should be evaluated according to the following parameters given by the manufacturer.

--- Set pressure, p0;

--- Exhaust rate under pressure p0 deltap, Fe;

--- Termination pressure, pc;

--- Operating temperature range, namely the underground, anti-frost or outdoor installation.

A.4.2 If p0, p0 deltap and pc values measured before and after the durability test are given by the manufacturer in a difference of 5% or less, the test by. In addition, when the pressure is lower than the termination of pressure, without air through the valve.

A.7.7 durability test procedures according A.6 cycle 1 x 103 times.

A.7.8 environmental (analog) set oven temperature (20 ± 5) °C, and maintain.

A.7.9 A.5 performed according to parameter test procedure.

A.8 Test Results

In accordance with A.7.2 and A.7.9 record p0m, p0m deltap pcm and value, respectively, with the manufacturer of p0, p0 deltap and pc Compared to the value. If all measured values are within ± 5% of the value specified by the manufacturer, type approval is given. Otherwise, the test fails.

B.1 Overview

Drying filter to a closed system is a prerequisite, according to a certain sized, so you do not replace within a year.

B.2 Symbols and p1 pPA 100000, unit. Pa (Pa) p2 pPE 100000, unit. Pa (Pa) p3 pAE 100000, unit. Pa (Pa) p4 pSV 100000, unit. Pa (Pa)

(PSV = pressure relief valve opening pressure of the relative value), unit. Pa (Pa) pm (p1 p2)/2 Average working pressure (absolute), unit. Pa (Pa)

T0 15 °C = 288K T1 T0 deltaT2 T2 T1 7.5K deltaT1 according to incremental (B.1) temperature unit. On [Kelvin] (K)

deltaT2 according to the incremental (B.2) temperature unit. On [Kelvin] (K) m1 at a temperature T1 and pressure p4 air quality m2 at a temperature T2 and pressure p4 air quality ma per kilogram of dried silica particles mass absorbed moisture, unit. g/kilogram (g/kg) msch dried silica particles gross weight, unit. kg/m 3 (kg/m3)

V0 extracted air volume (leak detector is discharged through the valve), unit. m 3 (m3)

Volume Vk double gap = 1m3 The maximum volume Vmax leak detector for double gap, unit. m 3 (m3)

VTF filter drier volume, unit. liter (L)

Conventional gas constant R (here, air) = 287J/(kgK)

Air flow rate QL leakage caused unit. m 3/year (m3/a)

The air flow rate Qs exceeds the pressure relief valve to open when the pressure caused by temperature changes, unit. m 3/year (m3/a)

Qgas total flow rate of air (Qs QL), unit. m 3/year (m3/a)

B.3 Dry filter air flow rate

B.3.1 Temperature Effect

Because of a gap in the double rise in temperature leads to a pressure increase of the reaction pressure relief valve, the pressure relief valve is equal to the amount of gas dried

NOTE filter exhaust air flow full amount again.

Referring to the output pressure in accordance with Equation (B.1) temperature increment derived as follows.

deltaT1 = T0 (p4/p1-1) (B.1)

Taking into account the average working pressure pm, according to the formula (B.2) derived deltaT2.

deltaT2 = T0 (p4/pm-1) (B.2)

Therefore, the temperature T1 can be calculated according to equation (B.3).

T1 = T0 deltaT2 (B.3)

Therefore, only the temperature is greater than from the time T0 to T1, the pressure relief valve will cause a reaction.

The average temperature increase leak detection medium exceeds T1 (dry air), then that takes into account the following temperature higher than the average temperature of the warm summer.

--- After 60 days the temperature rises 10K (greater than T1);

--- 60 days temperature 5K (greater than T1).

The average temperature increment mentioned before, if within the 120d reaches 7.5K, should also be taken into account.

B.3.2 Loss calculation

Calculate the air quality in accordance with the formula (B.4) and formula (B.5). m1 = (p1 x Vk)/(R x T1) (B.4) m2 = (p2 x Vk)/(R x T2) (B.5)

, The resulting air quality emissions according to formula (B.6) by the formula (B.5) minus formula (B.4).

T1- (B.6)

Thus, the formula (B.7) gives the emissions of.

V0 = deltam x R x T0/p0 = T0/p0 x Vk x T1- (B.7)

Double gap unit of measurement. cubic meter/cubic meter (m3/m3)

It shall be calculated by the following formula (B.8) according to the filter by drying air flow rate.

Qs = V0 x 120 (B.8)

B.3.3 Impact of leakage

Suppose leak detection system, there are 2.0L/d average leak rate that 0.73m3/a.

B.3.4 Results

According to the formula (B.9) obtained dried filter air flow should be.

Qgas = Qs QL (B.9)

Double gap volume by 1m3 dollars.

B.4 Filter drier volume calculation

For ease of calculation, temperature 30 °C, humidity of 80% air. Moisture in air at atmospheric pressure conditions fL = 25mL/m3 = 0.025kg/m3.

Install filter drier, so that air drawn according to equation (B.9) flow rate of drying to a residual moisture content of at least 10%. That is according to the following Formula (B.10) calculated in dry filled with dried silica particles filter year after the volume.