Size Deaerator
- For a separate surge tank as part of a two-tank (2T) system, refer to Size Surge Tank.
- For a two-compartment (2C) deaerator having combined deaerator and surge compartments, refer to Size Deaerator (Two-Compartment).
Pump Flow Rate
Each pump on a deaerator is sized based on the total load of boilers fed by the specific pump. For boiler feed pumps running ON/OFF, the pumps are controlled by a boiler level controller.
Deaerator Receiver Size
The receiver size on deaerators is typically based on the total system load (i.e., sum of all boilers fed by deaerator) with 10 minutes NET storage.3
Pump Discharge Pressure
Assumes proper discharge pipe size of a velocity of 10 ft/sec or less. Pump discharge pressure MUST BE ABLE to overcome the boiler safety relief valve setting plus 3% of valve setting AND meet all state and local codes. Discharge pressure of pumps based on the larger amount. This amount is either the Safety Relief Valve setting on boiler + 3% OR Boiler Operating Pressure + Valve Pressure Drops + Safety Margin.
If boiler and deaerator are on the same floor, enter a value of "0" (zero) for feet of head. If boiler is located on a floor above the deaerator, enter vertical height (in feet) from the pump discharge on the deaerator up to the inlet piping on the boiler.
If the pressure differential between the boiler operating pressure and the setting of the safety relief valve on the boiler is greater than 20 psig, consider replacing the safety valve with one rated closer to the boiler operating pressure. Otherwise the motor horsepower of the boiler feed pumps will need to be oversized to provide a discharge pressure sufficient to overcome the rating of the safety relief valve on the boiler. The higher motor HP typically would require a more expensive pump and increases ongoing operating costs.
Stand Height
On all deaerators, the available NPSH is 0 feet of head unless the deaerator tank is elevated above the pumps. To calculate elevation of stand, determine required NPSH of pump from pump curve and add 2 feet of head as safety factor. The result is the MINIMUM required stand height.
- Each pump on a deaerator is sized based on the total load of boilers fed by the specific pump.
- For boiler feed pumps running ON/OFF, the pumps are controlled by a boiler level controller.
- The receiver size on deaerators is typically based on the total system load (i.e., sum of all boilers fed by deaerator) with 10 minutes NET storage.
- If boiler and deaerator are on the same floor, enter a value of "0" for feet of head. If boiler is located on a floor above the deaerator, enter vertical height (in feet) from the pump discharge on the deaerator up to the inlet piping on the boiler.
- Assumes pressure drop through modulating valve of 10 psig or less.
- Assumes pressure drop through stack economizer of 20 psig or less.
- Assumes proper discharge pipe size of a velocity of 10 ft/sec or less.
- Pump discharge pressure must be able to overcome the relief valve setting of the boiler. Relief valve setting on the boiler should be adjusted or replaced so the setting of the relief valve is close to the actual operating pressure of the boiler.
- Pump discharge pressure MUST BE ABLE to overcome the boiler safety relief valve setting plus three percent of valve setting AND meet all state and local codes.
- If the pressure differential between the boiler operating pressure and the setting of the safety relief valve on the boiler is greater than 20 psig, consider replacing the safety valve with one rated closer to the boiler operating pressure. Otherwise the motor horsepower of the boiler feed pumps will need to be oversized to provide a discharge pressure sufficient to overcome the rating of the safety relief valve on the boiler. The higher motor HP typically would require a more expensive pump and increases ongoing operating costs.
- Pump flow rate is < 0.5 gallons/min (gpm). Contacting your Shipco® representative is advised.
- Pump flow rate is > 500 gallons/min (gpm). Contacting your Shipco® representative is advised.