differential pressure tester

[cenabet]

I am planning on buying a differential pressure tester with master orifice, to check my compression on my cylinders. There are couple out there but I don’t know which one is a good one that will last. Could you give me your recommendations please?

[Joda]

I have both an Eastern Technologies and an ATS compression tester, and they both work well. I see no practical difference between the two.

[DaleB]

I bought the ATS. THere's not much to go wrong with these. I looked at a bunch of the Chinese-made cheap ones available on Amazon... but not a single one of them says what size the orifice is. It makes a difference. I asked several vendors about it. Most simply didn't answer; one said it was a "trade secret", which I thought was the silliest way possible of saying they had no idea because it's just some generic thing they sourced from Guangzhou or wherever. Decided to spend the extra bucks on one that is at least sold by a vendor who has some clue what it actually is.

[skyfixer8]

The following link will tell you all you need to know about the test and the orifice used. https://www.aircraftspruce.com/catalog/pdf/servicebulletin.pdf