Bell & Gossett HS 601G Pilot Operated Pressure and/or Temperature Steam Regulators Series 2000 - Manual (Page 7)

Outlet
Balance
Tube
Bleed
Orifice
Signal
Feedback Line
Main Valve
Inlet
Pilot Inlet
Spring
Pilot
Air Supply
Feedback Line
Balance
Tube
Outlet
Bleed
Orifice
Main Valve
Inlet
Pilot Inlet
Signal
AP Air
Pilot
Air PRV
Regulator
High Pressure
Supply Air
Temperature
Sensor
Balance
Tube Signal
Temperature
Pilot
Outlet
Bleed
Orifice
Main Valve
Inlet
Pilot Inlet
Spring/Air Pilots Temperature Pilots
1. The 1/4" feedback tapping must be connected to the
downstream piping for either a spring or air pressure
pilot:
• Use 1/4 black steel pipe for the feedback line (B).
• Install a 1/4 NPT shut off valve (D) and union (C)
in this line to allow service of the pilot while
operating the system on the by-pass line.
• The feedback line must pitch away from the pilot
to avoid erratic operation, excessive fouling and
eliminate water pockets.
2. When the regulator is used with a heat exchanger,
connect the feedback line (B) to the heat exchanger
shell. A tee fitting can be installed in the heat
exchanger for a vacuum breaker connection.
3. For air pilot installations, connect the regulated air
pressure supply to the top of the pilot bonnet.
1. When only a temperature pilot is used, the outlet
tapping port must be reduced. Use the 1/8 x 1/4
NPT bushing (from the hardware kit) in the 1/4 NPT
outlet.
2. Insert the sensing bulb so the full length of the bulb
is exposed to the fluid whose temperature is being
controlled.
a) Use a 1/2 NPT compression fitting to install the
bulb at the outlet of instantaneous heaters and
in the middle of storage tanks.
b) The preferred bulb mounting when installed in
the system piping is illustrated below:
c) Optional dry well (separable socket) allows the
sensing bulb to be removed from the tank or
piping without draining the system.
• When using a dry well, coat the bulb with high
temperature grease or heat transfer compound,
to aid heat transfer.
• Make sure that bulb and dry well are fully
inserted into the fluid being controlled.
Temperature pilot bulb will be immersed in the heated
fluid. Before immersing, check compatibility of copper
bulb with heated fluid. Failure to insure compatibility
may cause property damage.
! CAUTION
System should be supplied with overheat protection
(such as temperature relief valve or aquastat solenoid
combination) at 10˚F over set temperature. Failure to fol-
low this warning may result in property damage, personal
injury, or death.
! CAUTION
Flow from System
Pipe Tee
Pipe Bushing
Sensing Bulb
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