What causes pump slippage?

What causes pump slippage?

What factors affect Pump Slip? There are three main factors: differential pressure, fluid viscosity, and, in the case of positive displacement pumps, clearance dimensions.

How is pump slippage calculated?

The slip of the pump formula is defined as the difference between the theoretical and actual discharge is calculated using pump_slippage = theoretical discharge-Actual discharge. To calculate slip of the pump, you need theoretical discharge (Q th) and Actual discharge (Q).

What is slip and negative slip?

Slip of a reciprocating pump is equal to the difference of theoretical discharge and actual discharge of the pump. If actual discharge is more than the theoretical discharge, the slip of the pump will become –ve. Negative slip occurs when delivery pipe is short, suction pipe is long and pump is running at high speed..

What is fluid slippage?

Fluid slip is the deviation in the angle at which the fluid leaves the impeller from the impeller’s blade/vane angle. A difference in pressure and velocity during the course of clockwise flow through the impeller passage can be observed between the trailing and leading faces of the impeller blades.

What is slippage effect?

Slippage is a phenomenon in which natural gas from a reservoir bypasses crude oil and water (basically liquids) that is released from the capillary openings of porous oil reservoir formations and approaches to the mean free path of the natural gas.

What are the effects of pump cavitation?

Perhaps the most obvious effect of cavitation on pumps is the material damage that cavitation bubbles can cause when they collapse in the vicinity of a solid surface. Eventually, this will lead to fatigue failure and the sub- sequent detachment or flaking off of pieces of material.

How do you get rid of pump cavitation?

How to Prevent Cavitation

1. Reduce motor speed (RPMs).
2. Install an impeller inducer.
3. Incorporate a booster pump into your pump system.
4. If possible, reduce the temperature of your pump, liquid, and/or other components.
5. Increase liquid level around the suction area.

Why is cavitation bad?

Cavitation causes pump performance deterioration, mechanical damage, noise and vibration which can ultimately lead to pump failure. Vibration is a common symptom of cavitation, and many times the first sign of an issue. Vibration causes problems for many pump components, including the shaft, bearings and seals.

What is NPSH pump?

The difference between inlet pressure and the lowest pressure level inside the pump is called NPSH: Net Positive Suction Head. NPSH is therefore an expression of the pressure loss that takes place inside the first part of the pump housing.

Why is NPSH important?

The purpose of NPSH is to identify and avoid the operating conditions which lead to vaporisation of the fluid as it enters the pump – a condition known as flashing. In a centrifugal pump, the fluid’s pressure is at a minimum at the eye of the impeller.

What is NPSH state its importance?

The NPSH curve displays the minimum required inlet pressure (expressed in m) allowing the pump to pump in accordance with the performance curve and in order to prevent evaporation of the pumped fluid so as to avoid cavitation inside the pump.

How do you maintain NPSH?

These actions, which are spelled out below, mainly involve lowering the NPSHR of the pump.

1. Increase the liquid level in the suction vessel.
2. Eliminate any flow restrictions in the suction piping (such as a strainer)
3. Operate at a flow rate less than the pump bep (see figure 3).
4. Install an Inducer, if available.

What does it mean if NPSH is negative?

The NPSH is supplied from the system and is solely a function of the system design on the suction side of the pump. If the liquid is below the pump, this becomes a negative value.

How is NPSH calculated?

Explanation: To calculate NPSH Available, take the source pressure , add the atmospheric pressure , subtract the losses from friction within the pipeline and subtract the vapor pressure of the fluid . The result equals the NPSHA (or Net Positive Suction Head Available) of your system.

How do you convert NPSH to pressure?

What is NPSH?

1. NPSH = Ps ‑ Pvap
2. absolute pressure = gauge pressure + atmospheric pressure.
3. h = 2.31p/SG.
4. NPSH = Ps ‑ Pvap = 1 + 14.7 ‑ 8 = 7.7 PSI.
5. NPSH = 2.31p/SG = (2.31) (7.7)/0.9 = 19.8 FEET.
6. NPSHA = Psg + Pz + Patm + Pvel – Pvap
7. NPSHA = Pt + Patm + Pzt – Pf – Pvap
8. Flow Area of Pipe = 3.14 x 1.52 = 7.07 square inches.

What is NPSH available?

NPSH Available (NPSHA): The absolute pressure at the suction port of the pump. NPSH Required (NPSHR): The minimum pressure required at the suction port of the pump to keep the pump from cavitating. NPSH or Net Positive Suction Head is a very important part of a pumping system.