Description
Fire Pump
Pumps are engineered with latest design concepts and engineering technology, these pumps are ideal for fighting fire. All fabricated parts are standardized and manufactured accurately for its excellent performance, increasing overall durability & reliable operation. Precision balancing of impellers provides mechanical stability, smooth operation and minimal maintenance. Rotating parts & Impellers are constructed with corrosion resistant material. Special metallurgies are also available on request. Simple pump design allows for in-line service without disturbing piping. They are available with electric, diesel, or Electric-Diesel powered sets.
TYPES OF FIRE PUMPS
1. END SUCTION FIRE PUMP
2. SPLIT CASE FIRE PUMP
3. VERTICAL TURBINE FIRE PUMP
END SUCTION CENTRIFUGAL PUMP
End suction centrifugal pumps get their name from the pathway the water takes to enter the pump. Typically the water enters one side of the impeller, and on horizontal end suction pumps, this appears to enter “the end” of the pump. Unlike the HSC the suction pipe and motor or engine are all parallel, eliminating the concern about pump rotation or orientation in the mechanical room.
Since water is entering one side of the impeller, you lose the ability to have bearings on both sides of the impeller. Bearing support will be either from the motor itself, or from the pump power frame. This prevents the use of this type of pump on large water flow applications.
The appeal of an end suction pump is usually its lower initial cost. If the pump can perform at a given rating and pressure, then this type of pump is adequate. If diesel-engine driven, another advantage is the ability to have an engine parallel and close to a wall (assuming proper air venting is considered). This can save space in a mechanical room piping layout.
SPLIT CASE CENTRIFUGAL PUMP
Horizontal Split Case (HSC) pumps are given their name due to the “split”” design of the casing, where the casing cover can be lifted off of the pump to expose the internal components. These components include the impeller, bearings, pump shaft, and so on. HSC pumps have two bearings, located on either side of the impeller, which are useful to withstand the large amount of vibration and thrust forces often caused by water turbulence in the suction piping. The pump casings are often designed to handle higher working pressures, and are often heavier. The durability of the HSC design allows the pump to be used for very large water flows. It should be noted that an HSC pump is not always mounted horizontally, it is possible to have the same durability design features and have the pump designed to be mounted vertically.
The HSC pump is often connected to either an appropriate driver by a coupling or driveshaft. When mounted horizontally, this can take up more floor space. It is because of a concern for floor space, that you do not see as many HSC pumps for lower flows.
The impeller of an HSC pump is dependent on even water flow entering the eye (or inlet) of the impeller. There are two entry points of water into an impeller of an HSC pump, which is where the term “double suction” is used. If water enters the impeller unevenly, hydraulic imbalance can occur and cause stress to the pump shaft or bearings. The need for smooth, laminar flow in the suction piping of an HSC pump is precisely why the NFPA 20 has strict rules regarding the length of straight piping required on the suction side of an HSC pump (see NFPA 20 2013 4.14.6.3.1, and 4.14.3.1). As a general rule, the larger the volume of water to be pumped, the more important it is to have smooth laminar flow of water into the pump casing.
The orientation of an HSC fire pump must be predetermined when such a pump is manufactured and installed. The pump must be built for either right-hand (clockwise) or left-hand (counter-clockwise) from the vantage point of the driver. For diesel-driven fire pumps, the pumps can only be operated at a clockwise rotation. Failure to pay attention to this can lead to a pump that must be taken apart then reassembled in the correct rotation in the field (if the pump is driven by an electric motor), or piping that must be rearranged in the case of a diesel engine-driven fire pump.
Finally, due to the extra bearings, larger impellers, and overall larger size of the horizontal split-case fire pump, the cost is higher when compared to a pump with a cheaper design. The higher initial cost does afford you a pump that will last longer, and will be easier to maintain or service when compared to other pump types.
VERTICAL TURBINE FIRE PUMP
Suction Assembly - Suction bell is furnished with an extra long bearing that strengthens and provides rigid support for the lower end of the pump shaft. Suction bell provides efficient flow into the eye of the first stage impeller.
Discharge Head - The rugged pump discharge head assembly is made of close-grained cast iron. It has smooth passageways that ensures efficient overall operation and provides an above ground connection to the discharge piping.
Bowl - The pump bowls have vanes cast integrally in them. These vanes are designed to match accurately with the impeller, and are smoothly contoured to guide the flow to next stage with maximum efficiency.
Impeller - Impellers are enclosed type, made of bronze / SS 304 and matched to the pump bowls. Each impeller is statically / dynamically balanced as per ISO 1940-1 to insure highest efficiency and vibration free operation.
Column - Pump column pipe shall be in sections not longer than 10 ft each. Column pipe is flanged type. Flanged connections are accurately machined to accept bearing retainers and are bolted together securely for proper sealing.
Shaft Seal - The shaft sealing is gland packing type. A lantern ring is furnished between the packing and it relieves pump pressure from the upper packing rings by bypassing the high pressure water through its relief ports.
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