FAQs

In a reciprocating pump, a specified amount of liquid is taken into the pump through the inlet valves and then totally displaced from the pumping chamber by the plungers through discharge valves. This reciprocating action generates flow only (pressure is created by the restriction to this flow after it leaves the pump). The pistons (plungers) are connected to a crankshaft. The revolutions of the crankshaft (RPM) regulate the displacement of liquid from the pump. The total pump output is in direct proportion to the increase or decrease in RPM. Larger pistons permit a greater volume of liquid through the pump. Changes in RPM fine-tune the ultimate flow of the pump.

Generally, centrifugal pumps are selected for larger volume, lower pressure applications, while reciprocating, positive displacement pumps are useful in higher pressure applications. A reciprocating, positive displacement pump can be 40-50% more efficient and electric operating costs can be 2-3 times less, so it may be best to select the reciprocating, positive displacement pump even for the 100-200-300 PSI applications
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There are several questions you need to answer before selecting a pump to be certain that the pump meets your application needs. The type of application, the material compatibility with the pumped liquid, the temperature, the duty-cycle, the available power supply and where it will be installed are important questions to be answered.

Pumping higher temperature liquids can increase the risk of cavitations and cause premature wear of the seals. Liquid viscosity and vapor pressure change with increased temperature. Operation above 130 F is permissible; however, additional precautions should be taken to protect your pump. Elastomer or RPM changes may be necessary. Booster pump feed is generally recommended.

Abrasive liquids can be very damaging to your pump. Since reciprocating pumps use seals and o-rings that mate to smooth cylinder and plunger surfaces, the type and degree of abrasiveness of the reclaimed liquid being pumped directly affects the life and service cycles of the pump. However some reclaim systems require extensive filtration to remove highly abrasive substances.

Hiro Nisha is ideal for this application. Each pump is selected and installed with appropriate HP to deliver a specific flow and feed into a common feed line to the system. The pumps can be as few as 2 or as many as needed and set to come on with additional demand or on a time schedule basis. Each pump is fitted with a pressure regulating valve to set the desired system pressure and a secondary safety valve. Once the system flow and pressure are established, the only variance in performance will be due to a change in the down stream restriction (generally clogged or worn nozzles). This type of set up is very popular due to its flexibility in capacity and its pump serviceability without bringing the complete system down.

Triplex pumps are normally quite versatile in the liquids they can pump, however such pumps do not handle gases, suspended solids, and liquids at very high temperature or high-viscous liquids.

Typically, suspended solids are not recommended for these pumps. Suspended solids can become trapped in the valves of the pump or other accessories and cause a malfunction. Some suspended solids may be a smaller micron size, but abrasive in nature

100-150 RPM is typically the minimum RPM for these pumps to assure proper crosshead lubrication. With a VFD, it is possible to use a 10:1 turndown ratio. Do not exceed the 100 RPM minimum. When the pump is operating at a lower RPM, it is recommended to gravity feed or pressure feed the pump inlet (no negative suction) to avoid starvation or cavitations.

The condition created by the formation and collapse of vapor bubbles in the process is known as cavitation. The energy released from the collapse of these bubbles during the suction stroke causes erosion to the interior surfaces of the pump. Metal parts become pitted and elastomers can tear. This condition can be the result of excessive liquid temperature, high vapor liquids, and long feed lines, spiking by-pass valve or excessive turbulence in the supply tank. Cavitation should be corrected as soon as detected.

Starvation is restricting the inlet liquid flow to the pump. This can be caused by undersized lines, too many elbows and fittings, clogged inlet filters, too many demands on the liquid supply line or an undersized supply tank. Flooded inlet from a baffled supply tank sized 6-10 times the system capacitor pressure feeding the pump is the best options. Make certain the line size is one size larger than the pump inlet port.

Many products expand and contract due to changes in environmental temperature or liquid temperature. The components in Hiro Nisha pumps are designed to withstand normal temperature changes. However, with sudden and severe temperature changes in liquid temperature (hot to cold), damage to the ceramic lined plungers may occur.

Water hammering occurs to some degree in all pressure systems. Water hammering occurs with the sudden stopping and starting of the liquid delivery in the supply lines of a pump. These sudden changes in water velocity, deliver an intense impact load down the entire water line to the pump and accessories. It often creates a hammering noise and therefore referred to as water hammering.

Continuous-duty is any application under a full load or cycles for 8-24 hours per day, 5-7 days per week.

You can find the specified amount on the table (given in O & M manual). Almost in all pump models, you fill the crankcase with crankcase oil until it reaches the red dot on the level gauge.

Please refer to our operation Maintenance manual.

This can happen due to foreign material lodged in the pump, improper manifold installation, thermal shock or dropping. IMPROPER INSTALLATION: Misalignment of the manifold can result a circular crack around the plunger. FOREIGN MATERIAL: A foreign solid becoming lodged between the plunger end and the head may result in a cracked plunger. THERMAL SHOCK: Cracking can be caused by thermal shock. This is when the ceramic has excessively heated and is then hit with cold liquid. The ceramic cannot respond to the sudden change in temperature.

There are many reasons why your pump might not be delivering sufficient discharge pressure. These are highlighted in our operation & maintenance manual. The most important thing to remember is that your positive displacement reciprocating pump only delivers a specific amount of liquid (flow) based upon the RPM at which it is operating. Pressure is created by the downstream restriction placed upon that flow. Items such as pressure regulators, nozzles, valves, line size, chemical injectors and other system accessories can affect the system performance and discharge pressure. It is most often one of these items (not the pump) that has failed or worn that result in a loss of discharge pressure.

For optimum performance, the pump should be operated in a forward rotation with the crankshaft turning towards the manifold. This takes full advantage of the oil bath lubrication.

The most important thing to remember is DO NOT wait until the pump is leaking or stops running before doing maintenance to other components. This may result in a very expensive repair or even pump replacement. In a new installation, check your seals and valves after 1500 hours. If no wear is seen, check again after each 500-hour interval and at the first sign of wear that will become your maintenance cycle.

Oil seals are generally replaced when bearings or other crankcase work is done. Visual inspection of the oil seals (both crankcase and crankshaft) should be done each time a seal servicing (Lo-Pressure and Hi-Pressure) is done to prevent unexpected failures.

Scheduled maintenance will vary with each application and installation. With the many variables in pumped liquids, inlet feed conditions, duty-cycles, temperature of liquid and accessories in the system, it is difficult to give a specific number of hours as a standard. For optimum pump life, you should establish a maintenance schedule that is specific to your installation.

It is always to take your pump for service to the original seller of the pump or equipment. You can also ask for the required services from the your region’s distributor.