Pressure Control across Ultra Wide Flow Rate Range

At Equilibar we talk a lot about the precision of our back pressure regulators. But what does that really mean? Today we're going to demonstrate pressure stability through a 40,000 to 1 flow rate ratio. We will monitor the pressure on the inlet of our regulator with the set-point of approximately 970 psi, starting at about 1 ml/minute of flow and increasing to above 40 liters/minute. Here we have an Equilibar back pressure regulator with a PTFE diaphragm. We are going to provide the setpoint to this back pressure regulator through this standard nitrogen pressure regulator here. We are applying about 960 psi to the setpoint pilot right now bringing nitrogen gas on the inlet of the regulator through this micro needle valve. We are going to monitor the inlet controlled pressure both with this pressure transmitter here and also with this differential pressure gauge. We are actually measuring the difference, the slight difference between the pilot set point that we are providing and the controlled inlet. Right now the inlet is about 4 psi higher than this set-point. For the flow rate coming out of the regulator we are going to first measure with a bubble meter the micro flows in the range of 1 ml/minute. This is one milliliter. And then at higher flow rates are are going to pass through four decades of Dwyer rotometers, all the way up to the largest being 50,000 cc/minute. or 50 liters/minute. So right now we have our flow rates starting at near zero where this is a bubble meter. There's 1 milliliter between these two orange hash lines. A milliliter and a cc (cubic centimeter) are the same thing. You can see that we are right in the range of 1 cc/minute or 1 ml/minute of flow. Right at the moment our inlet is holding at about 969, 968 psi and we are about 7 psi over pressure, the inlet being higher than the dome very slightly. What we're going to do is gradually increase the flow and note of the 968 psi and the 7 psi over pressure. We are going to disconnect the bubble meter and switch over to our Dwyer rotameters This is a full range of 50 cc/minute. We are going to try to bring the micro needle valve up a little bit and control maybe in the range of 10 to 20 cc/minute This can be a little tricky to adjust these micro needle valves So we're now dropping down into the range of about 20 cc/minute and we are still at 7 psi over pressure and still at 969 psi, about the same pressure that we had before. Now we are going to switch to the 500 cc/minute max rotameter and then adjust the valve and bring the process flow up the nitrogen flow and let's try to go about 400 cc/minute. here we are coming up around 400 cc/minute and we're still at 7 psi over pressure, the inlet being higher than the set point slightly. And we've picked up about 1 psi. We are at 970 psi. Let's go again to 4000 cc/minute, or as its listed, 4 liters/minute . . . adjust the valve, we are coming up to about 4000 cc/minute or 4 liters/minute and we're still reading about 7 to 8 psi and 971 psi, so we have picked up another psi, maybe a total of 2.5 to 3 psi over pressure. Now we're going to go to our highest rotameter and try to go to 40,000 cc/minute or 40 liters/minute you can hear the gas coming out a little bit. Here we are 40,000 cc/minute. And we are about 8 to 9 psi over pressure and 973 psi, so we picked up a total of about 3 to 4 psi but what we have demonstrated is a range of 40,000 to 1 flow rate range. We started at about 1 cc/minute here, and we gradually increased it to 40,000 cc/minute. We picked up less than 0.5% of of change in the inlet pressure. Contact our engineers today to see how Equilibar can address your challenging pressure control application.