hydraulic cylinder testing - "proof" test
hydraulic cylinder testing - "proof" test
(OP)
When a manufacturer is testing new hydraulic cylinders I would expect a pressure somewhat greater than "working" pressure would be used. Is there a standard or common practice ( 120% ? ) that could be used as a reference?
If the "proof" pressure is known, would/should the testing include a sequence at that pressure?
thanks,
Dan T
If the "proof" pressure is known, would/should the testing include a sequence at that pressure?
thanks,
Dan T





RE: hydraulic cylinder testing - "proof" test
RE: hydraulic cylinder testing - "proof" test
ANSI Hydraulic Fluid Power- Systems Standard for Stationary Industrial Machinery
(NFPA/JIC T2.24.1-1990)
Integrity(Linear Actuators)
a) Size, mounting and member strengths shall be designed for maximum expected column loads at full extension or any other limiting position withing the stroke;
b) adequate structural and/or pressure sustaining strength shall be provided for applications where overrunning or sustaining loads are encountered;
c) all load ratings shall include the mounting attachments;
NOTE - Actuators with identical pressure ratings may be not suitable for that rating with various mounting configurations.
d)when the actuator is used as a positive position stop, the actuator shall be sized and mounting selected based on the maximum incurred loading induced by the machine member restrained if this loading is greater than the loading incurred during its normal work cycle;
e) piston rod material and finish shall be selected to minimize wear and impact damage.
Durability
Performance and durability requirements shall be as agreed to between the equipment builder and the actuator manufacturer.
Source: Fluid Power Designers'
Lightning Reference Handbook
Eight Edition
RE: hydraulic cylinder testing - "proof" test
Does the ANSI standard mention testing of production articles?
RE: hydraulic cylinder testing - "proof" test
The designs we supply will have some difference is failure pressure between bore size and working pressure ratings do to material availability limitations.
We do not have the ability to do life cycle testing but have in field performance data. When we did our seal life testing in the late 1990's at 7,000 psi we had system reliability problems that limited us to 35,000 bidirectional cycles. That was enough to prove the new design was better than the old design and get a patent. Next week we hope to start testing at 7,000 and 15,000 psi to qualify a pilot operated check valve, relief valve, rod seal design and accumulator seal design all at the same time. The rod seal and accumulator seal will be seeing 7,000 psi as will the pilot side of the P/O check. The nose of the P/O check and the relief will be seeing 15,000 psi.
Ed Danzer
www.danzcoinc.com
www.dehyds.com
RE: hydraulic cylinder testing - "proof" test
My first expectation is a new cylinder should be tested at some pressure > working pressure.
RE: hydraulic cylinder testing - "proof" test
If you have specified a 3500 psi working pressure you are probably getting a 3,000 psi cylinder and the seals used will degrade some just testing to 4500 psi. The manufacture may have qualified the design to a higher pressure but will limit the production testing pressure. We use the testing after assembly to check for leaks and blow by and limit it to the working pressure or 4,000 psi even on our 6,000 psi cylinders due to equipment limitations. We are upgrading the testing to 5,000 psi maximum later this month.
Ed Danzer
www.danzcoinc.com
www.dehyds.com
RE: hydraulic cylinder testing - "proof" test