Hmmm - Small Packard shutter that self closes

[Mkillmer]

Hi All,
I have a small Packard shutter that closes by itself. If the pressure is released from the bulb, the shutter closes - this is different to every other Packard shutter that I have. The other shutters I have (4 of them) will remain open if I take my thumb off the pressure hole in the bulb.
Is there a way to turn this "feature" off? My bulb/hoses have small leaks that have never bothered me until today - the longest I can keep the shutter open is 3 seconds.

Any ideas?

[cowanw]

You might try using it on it's side. But the problem of leaks should be fixed.

[Mkillmer]

I may not have been clear - the Packard shutter self closes regardless of orientation as soon as air pressure lowers. - any thoughts?

[Andrew]

sounds like it's new or recently refurbished so there's very low internal resistance... I sent one back to Packard to be refurbished and after it came back it tended to creep closed in normal orientation [but it didn't do it with the plunger horizontal].
Does it close straight away while the bulb is expanding? if so the bulb is generating a tiny negative pressure
it might help to release slower and make a larger hole in the bulb ?

[Carsten Wolff]

I have one with two pistons: One for instant and one for B. I can look for the difference between the pistons, but its packed away at the moment. Wasn't there a removable pin on some Packards that allowed you to set your piston to Instant vs Bulb?

[cowanw]

I may not have been clear - the Packard shutter self closes regardless of orientation as soon as air pressure lowers. - any thoughts?

You're clear, but the piston closes with gravity, with an air leak. If the shutter was upside down, it would not close. I have one in an ilex board which is mounted sideways and works fine in that position. I thought it was mounted wrong and mounted it 90 degrees around. It then behaved as you described until I moved it back the way it was originally.
Having said that you do need a non leaky set of tubing and bulb.