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Technical Tips & Information
Boiler Feed Pumps
One of the more demanding applications for pumps is boiler feed service. A boiler feed pump must be able to pump large volumes of water at temperatures of 200-250 degrees F, deliver proper pressure to permit the water to enter the boiler, and survive a tough environment.NPSH stands for Net Positive Suction Head. NPSH is the amount of pressure which must be present on the suction side of the pump to prevent water from boiling inside the pump which leads to cavitation and pump failure. To understand cavitation, take a moment to consider the boiling point of water.
25” Hg = 134 F boiling point
10” Hg = 192 F boiling point
0 psig = 212 F boiling point
5 psig = 227 F
10 psig = 239 F
Notice that water can boil at temperatures above or below 212 degrees F depending on the pressure. All Grundfos boiler feed pumps have NPSH readings in the 4-6’ range depending on the application specifics. A low NPSH reading insures that the water will not boil in the pumps causing cavitation which sounds like marbles rolling around in a can. Cavitation will cause seal and impeller failures within a very short span of time. Because Grundfos C series pumps have this low NPSH rating, you are assured of long trouble-free service.
Grundfos C series pumps can also be fitted with air cooled seals which will raise the maximum water temperature to 350 degrees F for very severe service applications. Grundfos also offers the LiqTec control unit which will automatically shut down the pump if it senses high temperatures and avoid a costly repair and down time.
Grundfos pumps are your best choice for boiler feed service.