Archive: Feb 2015

Pressure Testing DFT Check Valves

Check valves are known for their versatility and durability in diverse applications and processes. Many professionals rely on check valves daily, and as such, the valves they utilize must be of the highest possible quality.

Moreover, check valves must conform to industry standards to ensure successful results. DFT Inc. has manufactured check valves for over 70 years; our team of specialists fully understands the stringent demands of any application. One of our main goals is to prevent check valve failures before they occur—that’s why each DFT valve is thoroughly pressure and leak tested.

Test Methods       

DFT check valves are subject to MSS SP-61, an ANSI standard that institutes the requirements and acceptance criteria for shell and seat closure pressure testing. Proper pressure testing is conducted through various methods.

Shell Test

Valves are tested at a gage pressure no less than 1 ½ times the 100º F rating, rounded to the next highest 25 psi increment. The test medium is water, and the test should not be less than:

• 15 seconds for valves sized 2” and less
• 60 seconds for valves sized 2 ½” to 6”
• 120 seconds for valves sized 8” to 12”
• 300 seconds for valves sized 14” and above

Results: During the test, no observable leakage is allowed.

Seat Test with Water

Valves are tested at a pressure no less than 1.1 times the 100º F rating. The test medium is water, and the test should not be less than:

• 15 seconds for valves sized 2” and less
• 30 seconds for valves sized 2 ½” to 8”
• 60 seconds for valves sized 10” to 18”
• 120 seconds for valves sized 20” and above

Results: For metal seated valves, maximum allowable leakage is equal to 40 ml/hr of water per every inch of nominal valve size. For soft seated valves, no observable leakage is allowed.

After one hour, the maximum allowable leakage is 80 ml for 2” valves, 240 ml for 6” valves, 560 ml for 14” valves, and 800 ml for 20” valves.

Seat Test with Air

DFT valve models SCV®, Basic Check®, Vacuum Breaker, and Restrictor Check® are tested at an air pressure of no less than 80 psig. The test should not be less than:

• 15 seconds for valves sized 2” and less

• 30 seconds for valves sized 3”

Results:  For metal seated valves, the allowable leakage is 0.4 SCFH/inch of inlet size. For soft seated valves, no observable leakage is allowed.

Keep Our Test Info on File

DFT Inc.has created a Valve Leak Test Infographic so you can access these pressure tests in an easy-to-read file. The infographic illustrates the types of tests performed by DFT, as well as the standards to which we hold our valves.

To learn more about our specialized testing methods, please contact us today.