Model Engine Maker

Supporting => Boilers => Topic started by: natbr on May 08, 2018, 01:57:05 AM

Title: Automatic pressure regulator
Post by: natbr on May 08, 2018, 01:57:05 AM
I'm looking for an automatic pressure regulator for my 3' tug project.  The boat is powered by a PM Research #8 twin cylinder oscillating marine steam engine which seems quite happy running on 30psi or less.  I bought a P5B regulator from (China) which was well made but unfortunately, is designed to work optimally under more than 30 psi steam pressure. 

So I'm looking around for who else carries them -- lists them -- but are out of stock. 

Any other suppliers out there?


-- Nat
Title: Re: Automatic pressure regulator
Post by: Bobsmodels on May 10, 2018, 01:00:06 AM

Railroad supply used to sell regulators, I had two of them and they worked fine.  Inlet was 100# plus outlet on one line was 15#and on the other about 30# if I remember correctly.  I used one on the blower so I could just flip it on and it would not increase as the pressure went up.  The other was on a water pump for the same reason.  Just turn it on and it ran nice and slow independent of boiler pressure.  I know some guys used them on their oil burners to keep a constant blower speed I think.  I was in the live steam hobby almost 25 years and have been out it for about 10 so not sure who sells what.

Check with them and see what they have, go over to the Chaski live steam site and ask.

Title: Re: Automatic pressure regulator
Post by: bent on May 10, 2018, 05:00:11 PM
From reading the blurb on the ministeam site, you are looking for a fuel gas valve that regulates the boiler firing based on the steam pressure generated.  Bit different than just a pressure regulator like Bob describes.
Title: Re: Automatic pressure regulator
Post by: Zephyrin on May 10, 2018, 09:32:55 PM
I would bet that lighter springs on the Microcosm steam pressure regulator will do it...
You may ask to Microcosm to do that for you, there is over there, Jin, a very comprehensive and helpful modeller.
Title: Re: Automatic pressure regulator
Post by: derekwarner on May 11, 2018, 12:27:08 AM
Yes, I suspect that Jin uses a translator when reading his e-mails......I have also found him to be a most helpful person to contact when an question needs clarification

When posting  a note to Jin, I type in MS Outlook in English, then use the MS translator .to Chinese PRC..& copy this in at the top of the message

A P5B gas regulator is listed as providing steam pressures from 10 to 60 should be able to control the gas to exceed your 30 PSI steam requirement

Remember your gas tank pressure will vary dependent on the initial gas charge and temperature......I use disposable 70/30 gas cans and after filling my refillable gas tank the pressure available is ~~ 1.5 to 2.2 Bar.....have you checked your boiler gas jet [as being a limiting element?]

Title: Re: Automatic pressure regulator
Post by: natbr on May 11, 2018, 02:30:12 PM
Hi All,
Thanks for your suggestions. 

I did email Jin and he said that the P5B isn't that suited for low pressure and was working on a regulator for lower pressures -- so its useful range is below that of P5B (and certainly, the P5). As Derek noted, the stated range is 10-60 psi -- but what I found was is to get it to target say 30 psi  as the target pressure, I had to unscrew the adjustment knob to the point that its sealing o-ring started to show.  I asked Jin if I could shorten the adjustment plunger but he didn't think much of that option.   I will look at the option of using a lighter spring as Zephyrin suggests.  I'll let you know everything goes.

Thanks again for your thoughts!

-- Nat
Title: Re: Automatic pressure regulator
Post by: derekwarner on May 13, 2018, 04:38:08 AM
Pat ......I have to restate that Jin is a great guy to deal with ....however something is wrong here

If the Microcosm P5 [single diaphragm] regulator is marketed as 'providing steam pressures from 10 to 60 PSI' , then it must perform as stated

If it cannot achieve the stated performance [and the manufacturer acknowledges this], then you as a consumer should have or be offered a PayPal  $refund or credit applied to your account

My steam plant has a French manufactured V71 [single diaphragm look a like] gas regulator and it functions perfectly to provide a true gas regulation function when the pressure signal from the boiler is my case ~~43 PSI [or just under the 3 Bar boiler relief valve setting]  is reached

[during initial test settings, I had the V71 operating at ~~20 PSI cut out......]

I have seen a Microcosm WEB video  twin diaphragm gas regulator [P8?] set on a with totally acceptable 'cut out - cut in' regulation function

From this, could I suggest that you go back to Jin.......there must be an answer from his range of products............


Title: Re: Automatic pressure regulator
Post by: Noitoen on May 13, 2018, 11:06:10 AM
The last page has plans for a gas regulator (