BS EN ISO 15848-2: Production acceptance test of valves
ISO 15848 Part 2 specifies test procedures for the evaluation of external leakage of valve stems or shafts and body joints of isolating valves and control valves intended for application with volatile air pollutants and hazardous fluids.
End connection joints,vacuum application,effects of corrosion,and radiation are excluded from ISO 15848 Part 2.
The production acceptance test is intended for standard production valves where fugitive emissions standards are specified.
5 Test conditions
5.1 Test fluid
The test fluid shall be helium gas with a minimum purity of 97 %by volume.
5.2 Leakage measurement
Leakages shall be measured by sniffing method in accordance with ISO 15848-1:2015,Annex B,and shall be expressed in ppmv.
5.3 Test pressure
The test pressure shall be 6 bar (1 bar=0,1 MPa=105 Pa;1 MPa=1N/mm²),unless otherwise agreed by the manufacturer and the purchaser.
5.4 Test temperature
The test temperature shall be at room temperature as defined in ISO 15848-1.
6 Test procedure and eva luation of test results
6.1 Measurement of stem (or sh aft)seal leakages
The procedure for measuring the leakage of stem or shaft seals is as follows.
a) Half open the test valve and pressurize to the level specified in 5.3.Measure the stem seal leakage
using the sniffing method in accordance with ISO 15848-1:2015,Annex B.
b) Then,fully open and close the pressurized test valve five times.
c) Half open the test valve after the mechanical cycles and measure the stem seal leakages as in a).
d)If the reading exceeds the values of the required tightness class according to Table 1, the test shall be considered as having failed.A corrective action shall be proposed and agreed with the purchaser or the lot of valves shall be rejected.
Table 1 —Tightness classes for stem seals
| Class | Measured leakage ppmv | Remarks |
| A | ≤50 | Typically achieved with bellow seals or equivalent stem (shaft)sealing system for quarter turn valves |
| B | ≤100 | Typically achieved with PTFE based packings or elas- tomeric seals |
| C | ≤200 | Typically achieved with flexible graphite-based packings |
| NOTE Measured by sniffing method as defined in ISO 15848-1:2015,Annex B. | ||
6.2 Measurement of leakage of body seal(s)
The procedure for measuring the leakage of body seals is as follows.
a) Half open the test valve and pressurize to the level specified in 5.3.After the test pressure has been stabilized,detect leakage of the body seal(s)in accordance with ISO 15848-1:2015,Annex B.
b)Ifthe reading exceeds the value of the required tightness class according to Table 2, the test shall be considered as having failed.A corrective action shall be proposed and agreed with the purchaser or the lot of valves shall be rejected.
Table 2 —Leakage from body seals
| Measured leakage ppmv |
| ≤50 |
| NOTE Measured by the sniffing method as defined in IS015848-1:2015,Annex B. |
