Video: Flow control & small delta-P
13 July 2021
By Armand Bergsma & Sem van de Peut
Flow Control by PCS
In this blog, we present a new video that demonstrates how the precision control products of PCS can be beneficial also beyond the scope of pressure control. PCS regularly applies the unique and innovative technologies to the control of other process parameters such as – in this case – flow control.
In this video, Sem demonstrates a set-up that he used to provide an answer to a customer’s who asked us about the minimal delta-P required to control flow.
Flow control & the impact of pressure differences on control stability
The set-up that we show you in this video has been built to answer a customer’s question regarding the minimally required pressure drop over this Coriolis mass flow controller. Wouldn’t the pressure delta be so small that it would endanger the flow control stability?
The video set-up consists of:
1 Coriolis flow sensor combined with an Equilibar back pressure regulator with integrated proportional valve (in this case an ML120 with U3L1 Equilibar valve).
1 Equilibar back pressure regulator controlled by 1 dual valve electronic pressure controller.
2 delta-P sensors.
In the customer’s example, the flow controller is built to dose a liquified gas into a reactor, starting at atmospheric pressure. “How stable could this flow be controlled despite a (small) difference in the upstream and downstream process pressure?”, the customer asked us.
Equilibar control valves & stability in pressure control
One of the main characteristics and a unique feature of the Equilibar back pressure regulator is its neglectable amount of pressure drop. This is inherent to the operating principle of the Equilibar valve. See our How it Works page including video if you want to explore this further.
As we see in this video, the total delta-P over the mass flow controller is not even 1 bar. This pressure drop is mostly caused by the Coriolis sensor. In this particular case, the pressure drop over the Coriolis sensor is 77 mbar when dosing at a flow of 30 gr/h of air.
This mass flow controller is capable of controlling over a range of 0.1…200 gr/h of liquid or gas, with a delta-P of 200 bar down to 1 bar. The Coriolis measuring principle is media-independent and super accurate, which means you can control almost every liquid, gas, or liquified gas (like for example C2H4, C3H6 or CO2) with this combination. The Cv rangeability of the Equilibar dome loaded control valve is 0,07 down to 10E-8, making it a “One-Size-Fits-All” mass flow controller.
Available versions & materials
0,1…200 gr/h (Pmax 200 bar)
1…2000 gr/h (Pmax 200 bar)
30…30.000 gr/h (Pmax 200 bar)
100…100.000 gr/h (Pmax 100 bar)
400 bar versions are available on request.
As a standard, all wetted parts are SS316, PTFE, Glass and Viton or Kalrez seals.
Hastelloy C276 is available for almost every combination, except for the 0,1…200 gr/h version.
Want to know more?
Feel free to contact our engineers if you want to discuss possibilities for your flow control application. We’ll be happy to share our expertise and propose a “best match” product solution for your particular process requirements!
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