Teflon Bronze Throttle Valve
See also Throttle Valve.
News about an off-the-shelf Teflon/Bronze Throttle Valve
Modeltec, May 1984
One of the most important accessories on any boiler is the valve used to control the flow of steam to the power unit. Our transatlantic cousins call this device a regulator; we Americans refer to it as the throttle. No matter what name you give it, if it does not function properly, it could be called something less than nice!
There are definite specifications that a good device should meet. There must be complete control over the flow of steam, and the ability to stop, to start, and to be able to meter the flow is of utmost importance. It should be easy to operate and, once in position, should stay in that position until moved by the operator. It must be reliable and (a final feature) not be too expensive or complicated.
The bronze-teflon combination featured in the valve shown in the photos meets all those specifications. Perhaps the only real disadvantage is its size. It is sometimes difficult to place it in the smokebox of a smaller-scale locomotive.
However, in the photos, it will clearly be seen that it can be placed in a smokebox of 5-1/4 inch inside diameter and, with some careful planning, it could, no doubt, be placed in a smaller one.
The valve can be obtained from Grainger.com and the stock number for the 1/4 inch pipe size is 5X713. Ed: This product is discontinued. Please consider one of these instead.
- Manual Two-Way Ball Valve: 3/8 in, 316 Stainless Steel, Straight Valve Body, RPTFE
- Manual Two-Way Ball Valve: 1/4 in, 316 Stainless Steel, Straight Valve Body, RPTFE
The price of the smallest valve (the 1/4" size) is less than $10.00 Ed: 1984 dollars.
The valve may be mounted inside the boiler, but it works well for the front end mounting. It is best to shield it from the direct path of the flame... and, if you don't believe fire rushes from the front end of the tubes, just peek down the stack at night when the blower is on!
The valve shown in the photos was mounted in a locomotive already in service (as a replacement) so it was necessary to adapt the valve to the existing steam lines. The steam supply line from the dry-pipe came forward as two lines, one on each side of the stack.
This made it necessary to make a special mounting to support the valve and to drill the side for entry of the lines. It would have been much better to have only one steam line from the dry-pipe, but it was easier to adapt the valve than to rebuild the front end of the boiler, which would have required removal of the boiler from the frame.
"How long do they last?" I'm not really sure. We've been placing them on boilers for more than ten years and have not had to replace one yet.