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* Refer to Fig. 99 when dripping steam
supply main to condensate return.
NOTES:
1. Flange or union is located to facilitate coil removal.
2. When a bypass with control is required.
3. Flash trap can be used if pressure differential between supply and
condensate return exceeds 5 psi.
4. Coils with different pressure drops require individual traps. This is
often caused by varying air velocities across the coil bank.
5. Dirt leg may be replaced with a strainer. If so, tee on drop can be
replaced by a reducing ell.
6. The petcock is not necessary with a bucket trap or any trap which
has provision for passing air. The great majority of high pressure
return mains terminate in hot wells or deaerators which vent the
air.
Fig. 100 — Multiple Coil High Pressure Piping
Unit
Unit
a39-4311
* Refer to Fig. 99 when dripping supply to return.
NOTES:
1. Flange or union is located to facilitate coil removal.
2. When control valve is omitted on multiple coils in parallel air flow.
3. When a bypass with control is required.
4. Coils with different pressure drops require individual traps. This is
often caused by varying air velocities across the coil bank.
Fig. 101 — Multiple Coil Low Pressure
NOTES:
1. Flange or union is located to facilitate coil removal.
2. To prevent water hammer, drain coil before admitting steam.
3. Do not exceed one foot of lift between trap discharge and
return main for each pound of pressure differential.
4. Do not use this arrangement for units handling outside air.
Fig. 102 — Condensate Lift to Overhead Return
Coil Freeze-Up Protection
WATER COILS
If a chilled water coil is applied with outside air, provisions must
be made to prevent coil freeze-up. Install a coil freeze-up thermo-
stat to shut down the system if any air temperature below 36°F is
136
Control Valve
Note 1
(Notes 2 and 3)
Strainer
Gate Valve
15° Check Valve
for Breaking
Vacuum
*
Thermostatic Trap (1/2 in.)
Open Air Relief to Atmosphere
Dirt Leg (6 in.)
15° Check Valve
Float or Bucket
Trap (Note 4)
Note 1
Gate Valve
Piping Gravity Return
Steam Supply
a39-4312
Condensate
Return
a39-2992
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