A Case to Explain Flow Meter Switch Selection for Hydraulic Oil

Recently, there is a requirement of flow switch or flow meter. The flow device will be used for hydraulic lubricating oil, and this oil is used for bears. The new flow device will be used to replace existing mechanical flow switches. As the flow switch is very old, there is no related brand or other information available. Thus, the customer has been cooperated with us for many years and trust our service. They hope us to recommend proper solution, and we are glad to do accordingly .

Customer gave us related technical requirement, and the main items for this application are listed as below:
1.high pressure(about 6MPa)
2.high temperature(Max 150 Deg.C.)
3.Switch output for Max/Min flow
4.4-20mA or RS485 for flow value
5.economic solution will be batter

As the conditions above, it is easy to find its temperature and pressure are high. Thus,this is a big challenge for many flow devices. When select flow devices, the top consideration should be to select often used flow meters or flow switches,because that means high cost-effective and easy maintenance in future.
As it is oil, magnetic flow meter can't work well because oil is not good electric-conductive.
Then we recommend ultrasonic flow meters,ultrasonic flow meters have clamp on flow meter,insertion flow meter and inline flow meters. Multi-channel ultrasonic flow meters may be able to work for this application. But users pass it because of higher cost.

We also recommended oval gear flow meter, because oval gear type has a high accuracy and widely used for oil flow measurement. However, the pressure is high, it is not easy to make oval gear type with such high pressure. So over gear is not suitable.

Then, turbine flow meter is another kind of solution, though 150 Deg.C is also hard for turbine flow meter. Our turbine flow meters can support 6MPa for the pipe size. Because switch output is not often equipped with turbine meter, so we need to use flow controller to reach the function. Turbine meters can support 4-20mA and pulse output. For this application, we need to select 4-20mA output,then the analog signal output is transmitted to the secondary flow controller which can accept analog signal input. According to this conclusion, we suggest the solution and also tell them the reason.

But after that, the customer said the Max temperature is 70 Deg.C., not 150 Deg.C. When receiving this updating, we immediately recommend digital thermal dispersion flow switch which has no moving parts. This will ensure longer life and better performance. Our thermal flow switch can support Max 80 Deg.C. and Max 100Bar. Its accuracy can reach +/-2%. Meanwhile, we have a model which can be equipped with switch output and 4-20mA output. So thermal flow switch should be a very good solution for this application. With economic price and good performance, thermal flow switches have been widely used for water, air and oil (e.g. hydraulic oil, lubricating oil etc.).

Warm Tip: If you have difficulty in product selection of flow, level, sensor, etc, please feel free to contact us. Our experienced engineers team will recommend better solution. You won't need to worry about it.

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