# Help! non-metallic check valve balls



## placitassteam (Jan 2, 2008)

I am having problems getting the balls in the check valves of my ACC Mason Bogie to seal. I remember seeing a thread about Teflon or some other non-metallic balls that could be used that work well. The stock balls are 4mm in diameter. Any help on this would be greatly appreciated.


----------



## Kovacjr (Jan 2, 2008)

Winn, have you tried getting new ones and reseating? Mine doesnt seat all the time wither. I have a good amount of dings on the valve from the pump handle.... What is the lift of the ball? 

If you want the rubber balls, might have to look. Mcmaster does not have the viton in metric. And stainless are only up to 3.5mm 

How about making rivet and using a small 4mm Oring? Ive seen that work in the past too. Might have to adjust for the lift of the seal.


----------



## Pete Thornton (Jan 2, 2008)

I am having problems getting the balls in the check valves of my ACC Mason Bogie to seal. I 
Mine wouldn't seal properly, so I took the check valve apart and cleaned it. It works now. 

My check valve came from the parts dept, but I believe it's the same one. It unscrews at the large nut.


----------



## placitassteam (Jan 2, 2008)

Thanks Jason and Pete. Jason's O-ring and rivet valve is intriuging, I'll file that for future reference. I'll also try some cleaning. The valves are so bad that the pump ram wants to be all the way back with quite a bit of force. My friend Wesley saw this thread and called a few minutes ago and had found that McMaster-Carr caries 5/32 teflon balls, 100 for $12.xx plus shipping so we should have a lifetime supply!! On my home built Bogie I used what amounts to Goodall valve on the end of a tube that extends from the backhead almost to the front of the boiler. it works quite well and puts the cold water at the cool end of the boiler. Thanks again.


----------



## SalM (Jan 2, 2008)

A good supply of things we use..................

http://shop.maidstone-engineering.c...mp;order=1


----------



## Steve Shyvers (Jan 2, 2008)

I purchased some 3/16" nitrile balls from McMaster-Carr for $1.25 each for use in a hand pump. The seal was no better than with a stainless ball. Lift of the ball (1/32 or less), seat diameter, seat cut with d-bit, and ball chamber diameter were all per best practices. I wound up going back to stainless balls and polishing the seats with Bon Ami scouring powder and a stainless ball soldered to the end of a length of K&S brass tube. Still not perfect seals but a lot better. One day I'll try the nitrile balls again. 

Steve


----------



## Steve Shyvers (Jan 2, 2008)

Check the roundness specification for the teflon balls carefully. It's been a while since I looked at them in the McM-C catalog but remember something about the roundness tolerance being loose or that they have mold-marks on them. Something that made me think they were less than ideal substitutes for stainless balls (for which there are various grades and tolerances too.) 

Steve


----------



## lotsasteam (Jan 3, 2008)

Nitrile balls,thats what they are called ,only source i know is Ralph Reppingen in germany(Regner might sell e'm also!!!! 

Manfred


----------



## Gary Woolard (Jan 2, 2008)

Aww heck.. please excuse me if this sounds like I'm trying to hijack the thread, but as a new Acc Mason Bogie owner as _WELL_ as being a live steam Newbie, I just gotta ask -- what IS a check valve? Does it have anything to do with the axle pump? ('Cause sometimes my axle pump seems to work, sometimes it doesn't, no matter how many turns of the screw..)


----------



## Semper Vaporo (Jan 2, 2008)

A "Check Valve" is a "one way" valve. It is usually attached directly to the boiler (where it is called a "Clack Valve" due to the noise the full sized ones make when the valve closes) so that water can be forced into the boiler against the pressure in the boiler but the water/steam in the boiler cannot escape from the boiler.

It works by having some sort of movable partition in it that is held against, and seals with, the water inlet by the pressure in the boiler. If the pressure at the inlet is greater than the pressure in the boiler then this partition moves out of the way and water flows through the valve and into the boiler. The partition can be a flapper (similar in action to a toilet flush valve, but metal instead of rubber) or in the case of miniature boilers, it is often a spherical ball. The Check Valve is usually mounted such that the inlet is at the bottom so that gravity can aid in causing the moveable partition to land over the inlet. In the full sized world, the valve might be mounted horizontally and the moveable partition guided into place by a spring.

In miniature engines with an axle pump there is usually a "bypass valve" also. Since the axle pump works whenever the wheels are rolling it is possible to over fill the boiler due to the continuous pumping, so a hand operated valve is "TEEd" into the pipe between the pump output and the bolier Check Valve. The output of the ByPass Valve is just a pipe to the tender water tank. If the Bypass Valve is OPEN then the axle pump output will simply flow back to the tender and no pressure can build to cause the Check Valve to open. If the Bypass Valve is closed then the pressure from the axle pump operation is applied to the Check Valve and water will (hopefully) flow into the boiler.

If the check valve is leaking then the boiler water or steam will travel to the Bypass Valve, which if it is open, will let the water/steam go to the tender. If the Bypass is closed then the steam/water travel back down the pipe to the axle pump where it should be blocked by the outlet valve of the axle pump. If that valve leaks then the inlet valve of the axle pump should block the pressure. Likewise, if it leaks, the water/steam should be blocked by the outlet valve of the hand pump in the Tender, and if it leaks then the inlet valve should block it. If all FIVE of the check valves in that string of valves leak then bubbles of steam will come from the inlet pipe of the pump in the tender... And I have seen that happen.

Anyway, the valve in that string of valves that is at the boiler inlet is called the boiler Check Valve.


----------



## Pete Thornton (Jan 2, 2008)

Here's a picture of the Accucraft check valve sold as a spare part. it screws into the backhead.

The LH piece contains the ball and spring, I think. You can see the white washer.


----------



## bille1906 (May 2, 2009)

I understand that the maximum lift of the check valve ball is 1/6 the diameter of the ball. On a 1/8' ball that would be about .020" and .026 for 4mm ball. 

I am beginning to think that the Goodall valve is the most foolproof. The main problem with the goodall valve is that it requires quite a bit of pressure to just overcome the tube resistance which adds to the differential between the boiler pressure and the pump pressure needed to work. It also takes up a bit more room. I have been playing around with loose fitting valves where the inside diameter of the silicone tube is only a couple of thousands smaller than the valve shaft. You can see this effect by noticing the pressure required to open the valve outside of the boiler with a squeze bottle. It is quite substantial on most goodall valves. I have made some with 1/8" id silicone tube and a shaft diameter of .128. I am using them in a regular goodall aplication. They don't leak back and are easier to pump than the ones I had before. I havent done one in a "Clack" application yet though.


----------



## Steve Shyvers (Jan 2, 2008)

Pete, 

The Accucraft check valve design is similar to a tire inflation valve. One was supplied on the backhead of my Accucraft S-12 0-6-0 to connect to the hand pump in the tender. There is a spring and plunger with a tiny o-ring. It seems well made, and does not leak. 

Steve


----------



## bille1906 (May 2, 2009)

Steve 
Bob T had a Mason Bogie at the last steamup that was making steam in the tender. He took the valve out and cleaned it and it worked ok after that. I also saw on another thread where there had been some problems with the tire valve design. 
I used something similar on my cylinder drain valves and they failed. I think the problem was that the steam pressure got between the rivit shaft and the o-ring from time to time causing leakage through there, even though the o-ring was seated in the valve body. I epoxied the o-rings to the shaft and that worked till the epoxy failed. I then went back to SS balls which now work fine. Naturally, the cylinder drains were much smaller and everything had to be perfect, which it wasn't.


----------



## Don5 (Nov 25, 2009)

Thanks, Rail Hobo Gary, for asking the question I was hesitating to ask. Jeez, I am such a newbie, I didn't know my Accu M Bogie _had _balls! I also have the same axle pump doubts as you seem to have. But then most of my hesitation definitely comes from lack of any live steam experience. This website and the live steam membership seem to be extremely anxious to help, but my LS knowledge is so minimal, I don't know what questions to ask. So far, I also think that I am the only person in Minnesota that has a live steam locomotive. Can't fall back on any hands-on help at this time. But I am learning, thanks to the MLS community! 

My MB seems to run fine, getting better with each run. I assume that is due to loosening up of tight parts. A current concern is regulating the boiler water - I do have the axle pump, but sometimes water disappears in the sight glass, so i give a couple of hand pumps, which sometimes results in the total water fill of the sight glass. I need more experience regulating the water level. I also end up with a lot of water puddles around my small oval track when I am done with a run - still looking for the source of that.


----------



## Steve Shyvers (Jan 2, 2008)

Bill, 

I should add that I never hooked up the hand pump on the S-12, so never made the check valve open and close repeatedly. As long as the check valve was unused it never leaked. It's since been removed and replaced by a threaded plug. (Used the one removed from the Ruby when I put a pressure gauge on her.) 

Also with reference to the photo in Pete's post, on the S-12 clack valve there were two red gaskets where the photo shows a white washer. The gaskets were sandwiched between and sealed the threaded connection between the LH and RH parts. The thickness of the gaskets determines the lift of the valve and the tension of the spring. 

Steve


----------



## bille1906 (May 2, 2009)

When Bob's unit was acting up, it was making water puddles also. The cause of that was the check valve leaking steam into the tender which was forcing the water to overflow. I didn't pay too much attention to how the water was coming out but I think it was coming into the cab area. Again, cleaning the check valve (tire valve type) solved the problem


----------



## Kovacjr (Jan 2, 2008)

Just a point of reference the Mason does not have the straight design valve as shown by Pete. They were used on earlier Accucraft models.


----------



## bille1906 (May 2, 2009)

Could be that the one I saw was a prototype or real early model or...I am just getting old.


----------



## HMeinhold (Jan 2, 2008)

Smallparts carries 5/32" diameter nitrile balls. This is equivalent to 4mm:

http://www.smallparts.com/small-par...1313508332 

Regards


----------

