Boylston device

CaptainTom

Can anyone identify this device, which is installed downstream of an old pressure reducing valve. The drip leg with the device in it is connected to the PRV like a pilot connection.  The device is marked "Boylston No. 1"

Zman

Heat Generator

That looks like part of an old heat generator. The part with the mercury has been removed. They were ingenius devices that allowed gravity systems to run at temperatures above the boiling point and still be a safe nonpressurized system.



http://www.oldhouseweb.com/how-to-advice/gravity-hot-water-heating-continued.shtml

Dave in QCA

Surge Chamber

it is a surge chamber. If you zoom in on the photo, you will see the PRV valve in the distance. The small pipe that exits the bottom of the surge chamber is connected to the control head of the PRV valve.



The Boylston valve is directly controlled by the pressure downstreem of the valve. However, the diaphragm in the PRV control head is a very heavy fiber rubber material. It is durable, but is not supposed to be directly exposed to steam. So, trapped air and/or condensate is the medium that operates the diaphragm in balance against two springs.



Often, the surger chamber is installed directly on top of the valve when installed in an upright position. In the picture, the PRV in the distance in installed upside down. Since the steam operating line will become filled with condensate, except for trapped air at the valve diaphragm, the surge chamber will fill with condensate and will be able to provide a reservoir of fluid necessary for the proper operation of the PRV through its control range without allowing steam into the control piping.

CaptainTom

Thanks

I appreciate the responses.  I also believe it is a surge chamber to keep direct steam out of the control valve diaphragm.