Procedure Of Centrifugal Pump Performance Test

The pump Performance take a look at procedure is disbursed as follows, however, it’s going to slightly modification supported pump marketer work condition and internal procedures.

The following takes a look at ar unremarkably disbursed in centrifugal pumps

Pump performance take a look at
Mechanical Run take a look at
NPSHr test

In that NPSHr take a look at is typically disbursed whenever the NPSH margin is a smaller amount than one meter.

Centrifugal Pump Performance take a look at the procedure

Step 1. The Flow Vs Head(q/H) take a look at

Normally the amount of points needed for mensuration relies on the Code used for pump producing that is., API 610, ASME, NFPA 20, Hydraulic Institute (HI one.6).

In the case of an API pump, six purpose mensuration ar needed.

These points can vary from a sub-minimum flow (Shut off) to a minimum of a hundred and twenty of BEP flow sub-minimum

Shut off mark
Minimum stable flow
An intermediate flow (flow between the minimum and BEP/ rated)
A point between ninety-fifth and ninety-nine of rated
Between rated and a hundred and fifth of rated flow, BEP (if rated isn’t among five-hitter of BEP),
At the top of allowable operation region (120% of BEP)
As per HI one.6, the performance takes a look at points ar supported pump varieties A & B.

Pump sort A:

These pumps are factory-made for special cases. For these pumps, the “Seven” measurement points ar needed.

Pump sort B:

These pumps are factory-made by production. For these pumps, the “Five” measurement points ar needed.

Note: All ASME pumps testing shall be as per HI one.6.

During the performance take a look at, the subsequent values shall be recorded at every takes a look at the point: suction pressure, discharge pressure, flow, revolutions per minute and power.

Centrifugal Pump Performance take a look at the procedure

Based on the flow (test points), the corresponding head is measured and planned within the Flow Vs Head curve.using the mensuration accuracy levels given for the category of a pump, drawing the q/H measured band;

Other Points check throughout the Performance test:

Speed:

One more major purpose to confirm the take a look at accuracy in pump speed. As per API, all tests shall be run at the rated speed + three-dimensional tolerance.

just in case the pumps at fifty cps (ie., in operation condition) however the take a look at the facility is sixty cps. The pump manufacturer has a necessary arrangement for reducing the frequency from 60Hz to 50Hz and comes through the operation speed.

However insensible a number of the pump manufacturer doesn’t have the ability to step down the frequency, in those cases, the take a look at the speed at sixty cps shall be at a similar pole speed as fifty cps provided the pump is rated for that in operation speed. If it’s not, then the pole speed should be reduced to the consecutive lowest price.

Mechanical seal:

Normally job seal is employed throughout the performance take a look at. Seals shall be check for leak throughout performance testing. If the visible leak is discovered the seal should be removed, inspected and repaired pro re nata.

The repaired and put in seal should be hydro take a look at with water at a hundred PSI or discovered throughout a subsequent running test to possess no visible leak.

Step 2. The potency take a look at

The potency guarantee is checked victimization a similar set of taking a look at measurements because the Flow Vs Head take a look at. Pump potency is shown planned against the flow as in the below figure. In most cases, the potency guarantee is such as the rated flow (q).

Step 3. Vibration measurements

At every performance take a look at information (except shutoff point) pump bearing housing vibrations are measured and recorded.

For between bearings pumps, vibration readings shall be measured on every bearing housing within the vertical and horizontal directions and on the bearing housing within the axial direction.
For overhung pumps, vibration readings shall be taken within the vertical, horizontal and axial directions

in the location of the bearing. These readings are taken at the pump drive and non-drive finish bearing housings within the horizontal and vertical positions.

Mechanical run Test:

The pumps are run at the rated flow till bearing temperatures have stabilized. Stabilization is achieved once the bearing temperatures have modified at or but two deg F in twenty min. when stabilization has been achieved, a four-hour mechanical run are performed at the desired rated flow condition.

The bearing temperature test:

Usually, this takes a look at is disbursed before all performance take a look at. this is often the proper time to debate the take a look at.

For pumps with flood oil or ring oil lubrication, sump oil temperatures are monitored throughout the performance take a look at. The temperature rise values are applicable to the period of the quality performance take a look at, generally one hour or less of operation.

For pumps with oil mist, outer bearing ring temperature shall be taken. If there are not any provisions for bearing temperature detectors, bearing housing skin temperature is measured.

For pumps with forced oil lubrication, temperature mensuration is taken within the outlet connections on the bearing housings.

Temperatures shall be measured before the beginning of the performance/mechanical run take a look at and at the conclusion of the take a look at before closing. Baseline temperature shall not exceed close temperatures.

Maximum allowable temperature rise higher than close temperature is as follows: (The values could modification slightly with totally different pump manufacturers)

Pumps with flood oil or oil ring – seventy degrees F (21C) oil temperature.

Pumps with oil mist – seventy degrees F (21C) white metal or bearing housing skin temperature.

For pressurized systems, the bearing oil temperature rise shall not exceed fifty degrees F (10C).

The NPSH test:

These are 2 common ways that are accustomed to doing the NPSH take a look.

Vacuum Suppression
Suction Valve choking

Vacuum suppression testing

The pump is provided from a closed tank with a continuing liquid level. Suction conditions ar varied by the employment of search air to extend pressure higher than atmospherical and a air pump to scale back pressure below atmospherical.

Suction valve strangling

This methodology is just used if the pump capability exceeds that of a closed check loop and therefore the pump is tested on a sump. The pump is provided from Associate in the Nursing open sump with a continuing liquid level.

A booster pump could or might not be used to simulate suction pressure on top of gas pressure looking at the characteristics of the pump. Suction pressure is reduced by strangling a valve on the suction piping of the pump in conjunction with motility off the booster pump.

In on top of 2 strategies, vacuum methodology results in ar additional correct and scientific results. unobscured by the presence of the valve. Refer on top of multidimensional language for vacuum methodology.

During NPSH testing, flow is about and command constant whereas the suction pressure is reduced incrementally. the overall developed head is monitored to see the suction point wherever a third come by the overall developed head is discovered.

The temperature of the check water is taken at now to see force per unit area. NPSH is calculated in accordance with the most recent revision of the Hydraulic Institute check commonplace.

Speed Corrections

Correction factors (applied to flow, Head, Power, and NPSH) have to be compelled to be used if the check speed of the pump will don’t match the rated speed. They are:

flow letter (corrected) = letter (measured) × (nsp/n)
head H (corrected) = H (measured) × (nsp/n)^2
power P (corrected) = P (measured) × (nsp/n)^3
NPSH (corrected) = NPSH (measured) × (nsp/n)^2

n = speed throughout the check

nsp = rated speed

ACCEPTANCE CRITERIA

After the pump performance checks, the results are checked with the rated conditions or security purposes. the appropriate tolerance vary is predicated on applicable pump producing points

For API 610:

The acceptable tolerance is

Rated point: +/-3%
Shutoff condition: +/-10%
Rated power < 104%
Efficiency isn’t together within the pump’s rated performance analysis
Overall vibration on the bearing housing measurements shall be but zero.12 in/s RMS. For knowledge points outside the POR (Preferred in operation Range) however inside the AOR (Allowed in operation Range), there shall be Associate in a Nursing allowable increase in vibration of half-hour.

For pump kind A: np – Contractor pump potency

For pump kind B: np – revealed, nominal potency

Conclusion:

As mentioned within the starting of this text, pump Performance check procedures could vary slightly in relation to pump manufacture internal check procedures. most pump manufacturers can meet the acceptance criteria mentioned during this article.

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