Why oh why is my pressure dropping?

Hello all, I need some help.
I kegged my first beer about a week ago. I set my MicroMatic regulator to 30 PSI and tried the shake routine to force carbonate.
I have 5 feet of 3/16" beer line in my system. The temp in my fridge is a steady 36F.
I was pouring foam like crazy, so I purged the Co2 and set my regulator to 10.7 PSI to serve.
I am still getting more foam than I want but that is another story.
My question, now that you have some background, is this:
Why after pulling a beer or two does my serving pressure fall to about 7 PSI?
I am not leaking anywhere...so I can't figure it out.
I hope some of the wise ones out there will chime in.
Thanks,
Dustin

Does it come back up?

First off, try checking the kegging sticky as I think you may have too little hose for the pressure. As far as the pressure dropping, I think you may need to adjust the regulator a bit better. On the regulator I've been playing with I need to go slightly past the amount and then it will settle in at the correct pressure.

I think you should be around 6-8 psi's with that short of a hose. Dont know enough to answer your other question but the high pressure is why you are getting all the foam.

bru-er said:

Does it come back up?

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It only comes back up when I force it to.

StankAle said:

It only comes back up when I force it to.

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How do you 'force it to'?

3/16" ID hose has a resistance of about 2lbs per foot... so if he has 5' of beer line, he is losing about 10PSI from the keg to the tap... I dont know that he needs MORE beer line. As for he pressure drop... that is odd, I have never had that problem as long as my CO2 is ON and beackfilling the headspace when I am dispensing.

ErikH said:

How do you 'force it to'?

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By turning up the co2 pressure using the regulator knob.

If your regulator is in the fridge, you're just experiencing the frustration we've all had in adjusting a cold regulator. It takes a few tries to get it just right due to the inflexibility of the regulator diaphragm at cold temps.

Your gauge could be inaccurate - my secondary regulator has a 0-40 PSI gauge that is wildly inaccurate. When it says 10 it means ~30. I keep meaning to replace it, but for now I set the pressure by charging the keg to 10 PSI with my primary reg and then ramping the secondary reg up until it just squeaked a little CO2 in, and backed off slightly.

Same thing happens to me. After I force carb, I purge and then crank the regulator down all the way, and then crank it back up to 12PSI or so. Once I pull a few pints the regulator almost always needs further adjustment. Just pay attention to it for a few pints - usually after this first adjustment it should remain stable.

Yuri_Rage said:

If your regulator is in the fridge, you're just experiencing the frustration we've all had in adjusting a cold regulator. It takes a few tries to get it just right due to the inflexibility of the regulator diaphragm at cold temps.

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Ahh thanks! It feels better to know that I am not some strange anomaly.
It's too bad that I have a dual regulator for my co2 tank. I can't think of a way to run 2 gas lines from the outside in to my Sanyo 4912. I bet I would get true readings at room temp.

Wade E said:

I think you should be around 6-8 psi's with that short of a hose. Dont know enough to answer your other question but the high pressure is why you are getting all the foam.

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I killed the gas to the keg, purged, and set the regulator to 8 PSI. This pretty much fixed my foaming problem!! I still get a head on the beer, but now it is just right.
Thanks!!
By the way, for my next keg, what do you recommend as a "set it and forget it" force carb PSI for my temp and beer line length?

I use 10' of line at 12 PSI, and it works great.

Moonshae said:

I use 10' of line at 12 PSI, and it works great.

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What ID hose, what temp?

3/16" ID, 38 degrees.

Doesnt 3/16" ID hose have a resistance of 2lbs/foot? If so, Id think that 5-6 feet would be plenty...

A follow up question:

Would having a cold regulator effect the readings on the low pressure gauge as well?

Cheers!!!