A Fresh Engineer (Customer) asked a question.
I need to make an automated hydrostatic testing station. I will use a PLC, pressure transducer, pressure transmitters, air pump, and solenoid valves. I have been looking on the internet for a couple days now to really understand how pressure transducers work, but I still don't understand how it will control a pump. I have an air pump that I am using now manually and would like to make it automated. How I will do this is use an hmi to type in the pressure needed and time needed to test the system. It will then send a current signal to the pressure transducer that it would need to convert to air pressure in the pump. I am not 100% sure how this works on an air driven pump but I would like to know if there any guides out there on using a pressure transducer on an air pump. I am worried that I might break something because I need a max pressure of 1500psi in the pump, and I don't want something to go wrong as I code and set up this hydrostatic testing station.
You need to be very careful. It's obvious you're trying to take on a bunch of things at once, but depending on the application, you could hurt or kill someone. In addition to figuring out how to make all of the things work, consideration needs to be given to safety devices and guarding as appropriate. You have to learn by doing but you also need mentorship and asking on this forum isn't necessarily the best place to get full system design recommendations. You could potentially be led astray which could wind up hurting you if you're not sure of what you're doing. When you start implementing automated control of high pressure hydraulic systems, it only takes a second for disaster to occur.
This is why I am trying to find the simplest approach to this before I start diving deep into the details of how each thing works. I just started doing research about 2 weeks ago, and don't worry I will not try to even start on buying components or even assembling this project before I even understand how and why each thing works this way. All I am doing now is figuring out how each thing works online; I will be taking my sweet time with this project and will be doing research and planning for another 4 to 5 months before I have a full set plan on what to buy. I have the safety devices also planned, using those solenoid valves and also some dump valves I will use those to relieve pressure if the system ever goes over 1500psi. All I need is some guidance for where to look for more knowledge and information on these systems, specifically pressure transducers. I cannot find much information online about how to program these with a PLC. I plan to use a pressure transmitter to know how much pressure is in the system so the PLC knows when to stop sending signals to the pressure transducer.
Jim Pytel/BIGBADTECH is probably the most comprehensive channel on YouTube for industrial controls. His delivery is dry, but man is it exceedingly thorough.
Hydraulics and Electrical Control of Hydraulic Systems:
Introduction to Fluid Power Systems (Full Lecture) - YouTube
Thank you, I will start taking notes and I won't stop for a while
Safety/Relief valves should not be solenoids, they should be spring operated mechanical valves.
You use an analog input to read the pressure in your high pressure system.
The I/P transducer is controlled with an analog output. The air pumps you listed previously have a pressure ratio to create high pressure from low pressure air. Controlling the pressure of the air also controls the pressure of the fluid.
The PLC will never "Stop" sending a signal to the I/P transducer, a proper program will have it continuously trying to maintain a set point (unless this is a leak-down test). When the test is complete and no pressure is desired, the output will drop to zero. When test is running, control with feedback from high pressure transmitter takes over.
So using the feedback/input from the pressure transmitter the PLC will calculate what pressure is needed compared to the pressure transmitter and always will be sending a signal to the I/P transducer to release pressure or give more pressure into the system.
Is there no way to automatically release pressure from the system after a test is done? I would like the PLC to tell a valve to open once the pressure test is completed.
Sure, you can program the PLC to whatever dump/bypass valve you want to release pressure from the system.
And pressure relief should be controlled by pressure,nor solenoid..i think youve mentioned it in other topic.
Yes, I will have pressure relief valves that are set at 1500psi or a bit above that so that nothing can be above damaged or explode. The solenoid valves will be there so the system can automatically release all its pressure after a test is done, there will be manual valves also just in case an operator wants to release the pressure manually. Let me know if everything I said sounds correct.