FLOW MONITORING

S

Thread Starter

Shreejith.P

I am looking for cost effective way of monitoring oil (mobil medium oil) flow to machine. What I need is a pulse output (DC) every 1 liter of oil flow (which will be used in PLC to calculate each flow) plus a digital read out of total flow and an external input to reset the total every month. I would prefer no moving parts and process connection can be 3/4" to 1-1/2". Any prefered brand which requires minimum maintenance?

Thanks and regards,

Shree
shreejith.p [at] uacan [dot] com
 
R
A vortex flow-meter will work provided the viscocity is not too high. They often have a pulse output that you can accumulate in a PLC or mechanical counter.

You could also use an orifice plate and DP cell with integration in a PLC however I think vortex will be more cost effective.

Give us the oil viscocity.

Regards
Roy
 
Vortex may be an expensive solution.

Most usually the answer is to use a positive displacement meter which will remain accurate over a wide flow rate range and a wide range of viscosities.

These meters can be very inexpensive. Triton is a name that comes to mind or FTI. Just do a search for PD Flowmeters. You should be able to find a meter for quite low cost.

If accuracy isn't too important but price is then there are also some fairly simple turbine type meters that are used for light oils.
 
R
The poster mentioned "no moving parts", I have used both the types you mention. Provided the oil is clean PD may work. Viscocity is a problem for turbine meter (vortex also) A DP type will work for sure, either an orifice plate or Integral orifice and DP cell.
Perhaps the poster will give us some more information such as Viscocity and flow rate.

Regards
Roy
 
The OP said he wanted "cost effective" and that he would "<i>prefer</i> no moving parts" and he qualified this by saying "anything low maintenance".

The balance of the OP's interest might be inferred as implying cost as the more important factor.

Hence, while the Vortex does satisfy the "no moving parts" criteria, it is not necessarily the most cost effective solution.

We could equally assert that technically, that panacea of flow, the coriolis would be the best choice.

It too has no moving parts and a wider flow range than vortex but is more expensive still.

We could, if we introduce coriolis, then expand the discussion to consider headloss but this was not among the OP's criteria.

We could justify coriolis as a candidate because various versions are increasingly used for heavy fuel oils including on board ships where PD meters are the industry standard not just for gas oils but for heavy fuel oils aswell.

One reason for PD meters, especially with oils, is that they are low capital cost and low cost of ownership. This is a typical and common application for them, indeed, they are used not just for lubricants and diesel and for heavy fuel oils but bitumens also.

So:
<b>PD meters</b>, low cost, wide flow rate range and excellent low flow performance and no significant viscosity concerns.
<b>Coriolis meters</b>, higher costs but no moving parts, but wide range and excellent low flow performance and no viscosity effects.
<b>Vortex meters</b> no moving parts, more expensive than PD but less expensive than coriolis, low flow limitations and viscosity sensitive.

The original poster does not give us any indication about dirt or head loss or any other factors.
If, however, the OP declares that the oils are dirty and that temporary blockage is a problem then we could move on to consider the FTI PD meters which are specially toleranced for dirty oils and include automatic viscosity compensation (based on temperature - they are calibrated across a range of viscosities) to compensate for the increased slip flow sensitivity.

I don't know how much more expensive the FTI meters are but we may find cost is then more of an issue and need to expand the search to include more meter types.

Simply based on the original post we can't anticipate any factors other than those proposed of which cost appears more important than no moving parts (and especially as capital cost often outweighs cost of ownership when trying to get purchase approvals).

Perhaps the OP will add some more detail so we may comment further.
 
R

Rohit Chandak

I would try to balance the product performance without much maintainance with low price & I think of either Turbine Flow Meters or PD Meter from reliable manufacturer as I believe that this are the two technology that works very well on viscous fluids that to be on small line sizes. Ultrasonic could be another option but would be expensive. There are Turbine Meter & PD Meters available in market that offers 5-Years warranty which itself speak about the quality that they deliver.
 
A very important consideration you left out is your accuracy requirements.

"Low cost" is a relative term as a low cost meter for +/- 2% is a heck of a lot less than a low cost meter if you require +/- 0.5%

Sam
 
R

Rohit Chandak

I fully support Sam's input & it is very important to confirm the accuracy statement since PD Meter/Turbine Meter prices heavily depend on the linearity being asked. Low Cost for me on this two product range would be linearity of +/-1% of reading.
 
Turbine meters are not particularly good with viscous fluids. Not only do we get a significant measurement offset we also lose linearity. Straight bladed rotors least of all. Helical bladed turbines are more viscosity tolerant but you do need to know the viscosity in order to compensate for viscosity variation.

But yes, for low viscosity oils they are a good option technically, provided the temperature doesn't change that much or where the viscosity temperature relationship is well enough understood (and viscosity doesn't vary with quality or aging of the oil) that temperature can be used as an indirect measure of viscosity so that an appropriate viscosity correction can be applied e.g. as with the FTI turbines.

But we are moving out of the low cost bracket here. Low cost turbines will probably require that you accept a much narrower flow rate range and lower accuracy. I'd suggest 1% would be a very ambitious call.
 
Shree,

The best solutions are:-
1. Integral Orifice with DP (hope the fluid is not high viscous) - Low cost solutions

2. PD Meter - use strainer (3/4" - the cost is low and low maintanance)

3. Coriolis Flow - High Accuracy & also high cost

Rgds,

 
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