Quartermaster frost free silcock

I have 2 question about this item:
First, there is a screw cap on the top behind the faucet handle that goes over some sort of circular plastic device with a small plastic point in the middle. Does anyone have any idea as to what this is is for?
Second, I installed this about a year ago and now there is a small drip
(about twice a minute) from the spout. Can this be repaired without replacing the entire thing?
Thanks in advance for any assistance anyone can give me.
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I have 2 question about this item:
First, there is a screw cap on the top behind the faucet handle that goes over some sort of circular plastic device with a small plastic point in the middle. Does anyone have any idea as to what this is is for?
Second, I installed this about a year ago and now there is a small drip
(about twice a minute) from the spout. Can this be repaired without replacing the entire thing?
Thanks in advance for any assistance anyone can give me.
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snipped-for-privacy@yahoo.com wrote:

The top cap is a vent. If it's leaking out of the faucet, you can put a new washer in. By chance did you solder it in without taking the stem out? If so and if you used enough heat, you could have burned up the washer.
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snipped-for-privacy@yahoo.com says...

Anti-siphon valve. It prevents you from siphoning "stuff" from outside back into your house.

From what I hear, yes. I've never done it. I just whack the thing out and put a new one in.
--
Keith

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Going on recollection alone, the device prevents water from being drawn back into the house in the event of a pressure failure. The one I'm thinking of also removes pressure from any attached hose or device when you turn it off. Water is intended to squirt out of the upper cap to relieve pressure, such as a hose. If it is the device I am thinking of, I hate it because it soaks you when you shut an attached hose off at the sill hydrant. Code in your area permitting, I'd take the thing out and throw it away, replacing it with a standard sill hydrant and a screwed-on back flow preventer.
Mark
snipped-for-privacy@yahoo.com wrote:

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Mark and Gloria Hagwood wrote:

If your's is doing that, it's deffective.
Code in your area permitting, I'd

Yeah, or a 50C washer is the other alternative

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