There is difference in opinion, how much maximum viscosity centrifugal pump can handle.

As a thumb rule the viscosity at which the efficiency of a Centrifugal pump drops upto 50% of the efficiency of same pump when pumping water then the said viscous liquid can be pumped by a Centrifugal Pump.

As Anis noted with his rule, at some point the efficiency of a centrifugal pump becomes so low that it would be uneconomic to use them.

A second consideration is when the viscosity is so high that the HI viscosity correction method can't be applied. At this point prediction of the pump performance is very difficult.

A third consideration is certain multistage pump types cannot cope with very high viscosities due to their internal design features.

Date publish by two different research work states:

a) Maximum viscosity centrifugal pump can handle : 440 cps
while other states
b) Maximum viscosity centrifugal pump can handle : 3300 cps

First person says at 440 cps, you require horse double power 2x, flow is reduce by 40% and head is reduce by 30%.

While the other states

Second person say at 440 cps, you prower horse power is increase by 33%, Flow is decrease by 4.4% and head is reduce by 7%.

Two different people two different claim. One who want to sell pump at any cost, while the other want to give correct fact to customer, to build repo with customer.

Quoting unattributed research without links doesn't really help pump purchasers come to a decision.

Hydraulic Institute 9.6.7 2010 is the accepted standard for viscosity correction and should be used when comparing pumps from different suppliers.

I've noticed a tendency of some suppliers to use obsolete or unrecognized viscosity correction methods. This just obsfucates things and makes it harder to select the best pump for the specific application.

thanks simon

I have got my answer.

This must be only applicable for end suction pumps.

Hydraulic Institute 9.6.7 2010 is applicable to all centrifugal pump types including OH, BB and VS types.

Like I said some suppliers prefer unofficial methods that help them look better. HI 9.6.7. should be insisted on as the baseline standard for comparison.

Simon

Small doubt, Question is not so important, but its good, i understand this properly.

HI is publishing guideline, other standards, books and report on pump. Do they have Test Facility Labs. where they can confirm such erratic result.

Dear Simon ,

As correctly conveyed by Mr.Bhalchandra ,we get two limits of viscosity correction for centrifugal pump. One is 200 Cst and second 500 Cst.Is it also compared with Specific Gravity to conclude the limitation.

Umesh, as I noted earlier, you need to provide attribution for the methods being used. Specifically:

What is the basis ? Theoretical or Empirical
How many data sets were used in creating and checking the method ?
Has it been peer reviewed and/or published for comment ?
Does it have wide acceptance of both manufacturers and users ?

If you can't answer yes to all those questions should you be relying on it ?

bhalchandra, I'm travelling without access to the HI standard so I'll check later this week.

However from memory, 9.6.7 uses >150 test data sets from various member pump companies. It is an empirical standard based on the data.

Hydraulic Institute being a group made up of pump manufacturers and users has no test facilities. However given the wide user base, problems tend to get reported quickly. I am aware of one paper on pipeline pumps that compared 9.6.7 to the actual results on many installations and concluded it delivered acceptable accuracy. I will see if I can locate a copy for you if wish.