Introduction

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Unit notes

Pump operates on the postive displacement principle. Pressure, typically, supplied by steam, is used to pump high temperature condensate or other liquids. However, unlike the FLOT which does not need electricity, the PP-HT uses electrical controls. It can transfer condensate for temperature up to 330°F where steam is available at 20 PSIG over the required discharge pressure.

Gravity flow

Condensate first flows into the receiver (top tank). Condensate then flows, by gravity:

• out the receiver (top tank) drain
• down the interconnected suction piping
• through the suction inlet (swing) check valve
• and into the inlet of the pump body (bottom tank)

Back pressure keeps the discharge (swing) check valve closed preventing condensate from flowing out the discharge outlet of the pump body. As the pump body fills with liquid, the float rises and the water level of the receiver (top tank) falls. During the filling phase:

• the steam inlet is closed
• the exhaust vent valve is open
• the suction inlet (swing) check valve is open
• the discharge (swing) check valve is closed

Valves open

When the float in the bottom tank reaches the high water position the float switch sends an electrical signal to close the exhaust vent valve, preventing air from escaping the bottom tank. Simultaneously, an electrical signal is sent to open the inlet steam valve allowing steam to enter into the top portion of the bottom tank.

Steam begins

With the inlet steam valve now open, steam enters the body (bottom tank). The internal pressure inside the bottom tank begins to rise.

Water pumped out

As the internal pressure increases within the bottom tank, the suction inlet (swing) check valve is closed, stopping gravity flow of condensate into the bottom tank and causing the water level of the top tank to rise. Simultaneously, the discharge (swing) check valve opens, as the internal pressure exceeds the back pressure in the discharge outlet. As condensate is pumped out, the water level of the bottom tank falls, along with the float.

Steam vented

When the float reaches the low water position, the float switch sends a signal to simultaneously close the inlet steam valve and open the vent valve. Steam from the bottom tank is vented to the top tank equalizing the internal pressure of the bottom tank with the atmospheric pressure of the top tank. After pressure is equalized, gravity flow of condensate is able to resume into the bottom tank. The fill/pump cycle repeats.