Easy 1/4" check valves?

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DianneB
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Easy 1/4" check valves?

Post by DianneB » Thu Nov 01, 2018 7:00 am

Does anybody have a simple method for making 1/4" check valves without special tools?

I am redoing the crosshead pumps on my 1960's vintage 1.5" scale American to improve the performance, which includes new cylinder/ram using O-rings for seals and opening the passages to (almost) 0.25" diameter to improve flow. I am using PM Research 1/4 brass pipe which has an ID of 0.186"

PM Research also sell 1/4-40 MPT check valves for about $20 that look pretty good. They are spring-loaded and I like the idea of positive sealing.

Don't know whether to buy check valves or if there is a simple way to make my own check valves that have little (or no) flow restriction???

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Builder01
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Re: Easy 1/4" check valves?

Post by Builder01 » Thu Nov 01, 2018 8:43 am

By special tools, do you mean a lathe?

David

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DianneB
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Re: Easy 1/4" check valves?

Post by DianneB » Thu Nov 01, 2018 11:19 am

By "special tools" I mean bottoming taps, D-bits, etc. I have a lathe and mill.

Harold_V
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Re: Easy 1/4" check valves?

Post by Harold_V » Thu Nov 01, 2018 3:56 pm

DianneB wrote:
Thu Nov 01, 2018 7:00 am
I am using PM Research 1/4 brass pipe which has an ID of 0.186"
Hmmmm. That doesn't quite make sense.

Pipe is measured by the ID, not the OD (in small sizes, 12" and under). Are you using tubing, or is it 1/8" pipe?

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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DianneB
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Re: Easy 1/4" check valves?

Post by DianneB » Thu Nov 01, 2018 4:39 pm

Harold_V wrote:
Thu Nov 01, 2018 3:56 pm

Pipe is measured by the ID, not the OD (in small sizes, 12" and under). Are you using tubing, or is it 1/8" pipe?
Makes perfect sense. The PMR brass tube is 1/4" OD with a wall thickness of 0.032 for an ID of 0.186". Since water travels on the inside of the pipe, 0.186 is the important dimension for figuring flow.

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Builder01
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Re: Easy 1/4" check valves?

Post by Builder01 » Thu Nov 01, 2018 6:02 pm

DianneB wrote:
Thu Nov 01, 2018 11:19 am
By "special tools" I mean bottoming taps, D-bits, etc. I have a lathe and mill.
Hi Dianne,

Here's the drawings for two different check valves I made for my loco. These are designed for 3/16" O.D. tubing, but, you certainly could increase things a bit to fit your 1/4" O.D. pipe, or, tube.

You will certainly need a lathe, and a mill for drilling the 4 little holes in the one part on the inline check valve, and the cross holes for the angle check valve. You can probably get away without bottoming taps. No D bits needed, but, you probably should use a reamer for the hole that the ball sits on and a way to make the face that meets it, very flat. A flat bottom drill bit works fine for that, you can grind one yourself offhand.

The images are of the drawings for the two different types of check valves, drilling the ports in the inline valve, and one of the inline valves disassembled, and then assembled. I have used a Viton ball in one of the inline check valves for my injector, and works just fine. I also made the body of the inline valve from hex stock so you can get a wrench on it.
23-780 Check Valves Only.jpg
DSCN1399 - reduced 2.jpg
DSCN1412 - reduced 1.jpg

Asteamhead
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Re: Easy 1/4" check valves?

Post by Asteamhead » Thu Nov 01, 2018 6:49 pm

DianneB,
This dfferent construction to the usual solution using a stainless ball might be of interest, too.
The seat maybe bored by means of a precise drill - or better - a 90° center drill (correct expression? "Senker") on the lathe.
The valve made of stainless steel or bronze on the lathe is to be tapered to the same angle of 90°. A viton O-ring is positioned into a cavern.
The O-ring should show just a little more diameter than the taper. That will endure tight seat in addition to a safe position when pressed to the valve seat (metal on metal!). A spring may be added onto the shaft.
The valve shown here has a inner diameter of 1/4 ". Outer diameter is about 11 mm, Diameter of the seat where the o-ring meets the valve 's body is about 8 mm due to 2 x diameter of the O-ring (1 mm) plus diameter of the bore.
The double check valve of a more simple construction :wink: is showing a similar design but with slightly enlarged valve bodies containing springs.
These simple constructions worked reliable for years with both water, hot water or even steam :D .

Asteamhead
Attachments
A Nathan double boiler check valve.red.jpg
The valve with o-ring is to be seen far left
Double boiler check valve.red.jpg
Double check valve of similar design

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Bill Shields
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Re: Easy 1/4" check valves?

Post by Bill Shields » Thu Nov 01, 2018 8:03 pm

The poppet idea is very workable and a favorite...but the balls work well if properly seated and contained so that they don't rattle and float

if you don't have flat bottom drills or D bits stop and think what a flat end mill is...drill a hole then finish it with the end mill.

I have been making flat bottom holes with end mills for decades as a means to create check valves.

Lately I have been purchasing checks them from a LSORR supplier / advertiser who has started using poppets in their standard valves.
Too many things going on to bother listing them.

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DianneB
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Re: Easy 1/4" check valves?

Post by DianneB » Fri Nov 02, 2018 5:32 am

Thanks for the designs! It has given me ideas ;)

James Powell
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Re: Easy 1/4" check valves?

Post by James Powell » Sat Nov 03, 2018 5:37 pm

Dad uses a set of metric end mills for making flats. Conveniently, they are generally just slightly larger than the common ball diameters, but not so much as to result in giant sideways float. (IE 5mm=.127", 8mm= .203.)

James

rkcarguy
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Re: Easy 1/4" check valves?

Post by rkcarguy » Tue Nov 06, 2018 5:33 pm

The difference you found here in this thread is due to pipe vs. tubing, two very different sizes.
Tubing is measured by OD, pipe is measured by flow size through the pipe, typically plus a bit, and then pipe threads are far larger. When tapping a 1/4" NPT thread, it's drilled ~7/16". 1/4-40 thread, would be drilled approx. .230" ?

To touch on the other comments, I make full use of, and abuse, other tooling. End mills, carbide router bits, even HSS auger bits will cut in softer metals with enough power and slow RPM.

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