in our company we have dosing pump to inject a chemicals those are high viscosity (named as DISPERSANT). earlier we used to have oval gear meter, but during winter the gear gets jammed. moreover the flow range is around 0-70L/h

we are looking for best solution any help? thanx!

 

Heat trace and insulate the source (tank of dispersant), the feed lines to the pump, the pump itself, and the discharge line to keep the viscosity low enough to pump even in the winter. Put a thermostat on the heat trace so it doesn't run in the summer time.

 

I used to work in an industry where we measured High Viscosity lube oil from cold to hot.

I tried all sorts of mechanical meters and finally ended up with an integral orifice plate that worked like a charm even though the renolds numbers were too high for the orifice calc program. The pump supplying the orifice was positive displacement (constant flow). I found to my surprise that the indicated flow change was insignificant from cold to hot.

A coreolis meter would work well if you have the budget.
Regards
Roy

 

dear Roy

thanx for ur reply, but micro motion as you said need budget. also micro motion as far as i know does not have low flow range as what we required (0-70L/Hr). in this case we are not sure about accuracy where the range for the meter was offered is (0-2180L/Hr) as per Emerson. Second issue is that it required two wires for data and two wires for power 110 AC.

 

thanx for ur reply, but heat tracing is not preferable by our process department.

 

Maz,

Micro Motion are expensive all right. I think though one would work if you chose the correct size. I would try a DP cell. If you have one handy you could try it out by makeing your own orifice or even try it across a partially closed needle valve.

Roy

 

Assuming a 500 cps viscosity a 1/4" Micro Motion would be ideal. Since the reynolds number is so low (about 6)many other flow technologies would have trouble, including integral orifice. The stated accuracy will be good down to about 20 LPH - really good turndown that low in a meters range, and you will eliminate all the expense of periodic maintenance and meter repair.

 

Please define the viscosity of the liquid that will give a better clarity. Petrol Instruments from Italy manufactures good quality PD Meters which can handle high viscous application to the tune of even 2000 cstk.

 

Rohit
thanx for you reply.
the Specific Gravity is (1.402)
the Viscosity is (358cP).
therefore correct me if i am wrong, doing simple calculation.

SG = Density/1000
then
1.402 * 1000 = 1402 as density
So
cstk = cP/density
then
2000 * 1402 = 2804000 cP
Is it correct or not?!

 

Responding to Mark
I know the viscosity is very high, my lube oil was very high also, off the scale for any orifice calculation, Foxboro refused to quote it but the fact is it worked like a charm.

The pump was a positive displacement type so i know the flow was quite steady. I expected the DP to be way off when the oil was cold but to my surprise it didn't change much at all.

I should point out that I was not trying to get an accurate result just replacing unreliable mechanical flow switches that were very protecting some very expensive equipment. I had tried all sorts of flow meters with no success.

I agree a coreolis would be the best choice if you need accuracy.

Roy

 

Oval gear meters have a very fine tooth and high pressure drop. Your viscosity is rising in the winter causing you problems. I recommend the old Flowdata pd meter. It used a lobed gear rather than an oval. They our now owned by FTI http://www.ftimeters.com/products/positive_displacement_flowmeters.htm

It will do the job for you.
Ed Ladd

 

I will go with Ed.