Seal options for boiler feed pump?

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Pwallace
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Joined: Mon Dec 05, 2022 2:39 pm

Seal options for boiler feed pump?

Post by Pwallace »

I am looking to repair a March boiler feed pump that is feeding an ottaway steam train in Northern California.

The steam side is 1.5” diameter and the water side is 7/8”. It’s apart at the moment so I do not have the stroke measurement.

I like the method in the Artisan steam engine piston rings using carbon filled PTFE but I am not finding material this offered at the common vendors in the 1” size. I have a mill and lathe of reasonable capacity.

It looks like this question about availability is posted every few years so this is my turn and I am interested in sources and alternatives.

The water side looks like cast iron with a very loose fit. The pump runs but it’s not filling the boiler so I would like to start with rings and then move through valves and plumbing.
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Bill Shields
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Re: Seal options for boiler feed pump?

Post by Bill Shields »

Use square braided packing and cut rings to fit.

Or use graphite tape and wind it around to fill the gland.

Been working for 100+ years, no reason to reinvent the wheel.
Too many things going on to bother listing them.
David Powell
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Location: Pickering Ontario Canada.

Re: Seal options for boiler feed pump?

Post by David Powell »

For soft packing to have a long life the piston it is fitted on should fit the bore with no more than about 5 thous total clearance, preferably less.
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Glenn Brooks
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Re: Seal options for boiler feed pump?

Post by Glenn Brooks »

Can you post photos of the pump? The only feed pump on my Ottaway is a 1” cylinderical pump mounted behind the port cylinder, next to the smokebox saddle. Never knew of a different style pump…
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Pwallace
Posts: 10
Joined: Mon Dec 05, 2022 2:39 pm

Re: Seal options for boiler feed pump?

Post by Pwallace »

It looks link I am able to post photos. I figured there would be post limits.
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This ottaway lives in the Bay Area and this March pump was a gift from one of the steam clubs in place of the injector. It’s not original and it struggles. I am hoping new rings help.

I will measure the grove and try to find packing. This is the water side and the existing rings look like cast iron.

I would still like to build the ring for fun but cannot source graphite filled ptfe or substitute.
Last edited by Pwallace on Fri Dec 09, 2022 12:50 am, edited 1 time in total.
Pwallace
Posts: 10
Joined: Mon Dec 05, 2022 2:39 pm

Re: Seal options for boiler feed pump?

Post by Pwallace »

Glenn Brooks wrote: Thu Dec 08, 2022 12:35 am Can you post photos of the pump? The only feed pump on my Ottaway is a 1” cylinderical pump mounted behind the port cylinder, next to the smokebox saddle. Never knew of a different style pump…
My understanding is that the small inboard piston on the port side is part of the optional air brake system.
7D9B22B9-6E44-4ABD-B49B-70CF60030A30.jpeg
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