Highly customized flow and pressure control for demanding applications
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An Alicat PC-15PSIG-D pressure controller
At Alicat, we are not only focused on accuracy but customizability. We give our customers the best solution for their application, whether that be in a humid, corrosive or heavily regulated environment. Every Alicat pressure, liquid or mass flow controller is completely tailored to the customer’s needs, from flow rates to communication protocols.
Alicat devices are as diverse as the applications they are used in. For example, one customer needed to control pressure in a test environment to adjust humidity. They purchased this device: PC-15PSIG-D/5P, 5IN; a 15 PSIG pressure controller. For many customers, this level of customization is enough to satisfy the application needs.
However, some customers need more.
A customer called us looking for a pressure controller that could control gas at 155 PSIG and handle flow up to 5,000 SLPM. The controller needed to be placed in an OEM box system but not lose interactivity from outside of the box. Within the box, the system was set to operate at temperatures up to 70 oC, and to be consistent with the rest of the equipment the device required analog signals and connections.
They also expressed some concerns to us: the system included pressure sensitive instruments which would break above 155 PSIG. Since the supply pressure was 180 PSIG this would damage or break the instruments, so the controller needed to measure pressure precisely at these sensitive instruments to ensure the pressure limit was not exceeded. While the operating temperature was 70 oC, the storage temperature of the box dropped down to -50 oC making condensation a big concern. With previous Alicat devices they’ve purchased, they noticed that the devices retained the last setpoint in its memory at power up, which was a security concern.
The instrument we designed for this customer addresses all of these concerns and is represented by the part number below:
PCRH3-100PSIG-RD-REMOTE-M12-40×55-SAE24-CC/CP, 5IN, RANGE (155 PSIG), P1: 180 PSIG, FLOW (5000 SLPM), GT, PUSP: 0, RD: 1.5’, REM: 1’
Now, this might look a lot like alphabet soup, but every letter and number lets us know exactly what this Alicat will look like.
Alicat PCRH3-100PSIG-RD-REMOTE high flow pressure controller with remote sense port and panel-mounting
Let’s walk through the part number:
High-flow pressure control: PCRH…40×55…P1: 180 PSIG, FLOW (5000 SLPM)
The first letters, simply put, designate that the device is a pressure controller, shown as PC. The RH afterwards means that this device has a pair of Rolamite valves in Hammerhead configuration. This allows for 5,000 SLPM high flow capacity. Hammerhead valves open and close simultaneously which doubles the surface area of the valve orifices, allowing more flow. Additionally, we built the valves with a custom size of 40×55, 40 being the orifice size (0.040”) and 55 being the number of holes in the Rolamite hole pattern. This specific hole pattern was determined to afford the greatest control across the expected range of inlet pressures (P1: 180 PSIG) and desired maximum flow rate (FLOW: 5000 SLPM).
Remote pressure sensing: 3
The customer wanted to maintain pressure after a delicate system of other instruments, but needed to regulate the airflow before it reached this system. The 3 signifies a remote sense port, which allows such pressure controllers to sense flow in a different area than where the valves are controlling the flow. This system is ideal in applications with limited space because the valve does not need to be located where pressure is being measured.
Customized pressure range: 100 PSIG…RANGE (155 PSIG)
The maximum pressure that the customer intended to control was 155 PSIG, so we modified the sensor range from the 0-100 PSIG stock sensor range to 0-155 PSIG.
Designed for panel-mounting: RD-REMOTE…RD: 1.5’, REM: 1’
This pressure control system was located inside of a box, but needed to be controlled from the outside. A remote display, noted as RD, allows the display to be mounted outside of the box, giving user access to all of the functions inside. RD: 1.5’ is the length of the cable that connects the remote display to the rest of the controller. The remote display was tested to withstand temperatures down to -50 oC, the lowest anticipated storage temperature.
With operating temperatures within the boxed system as hot as 70 oC, a REMOTE electronics package was specified. In high temperature scenarios which would damage the standard electronics, we separate the sensor assembly from the rest of the electronics package, so only the sensor interacts with high temperatures and the electronics are kept safe. REM: 1’ is the custom length of the cabling needed to connect the electronics to the sensor and flow body of the device.
Locking industrial connector: M12
The customer requested a locking M12 electrical connector to keep their system from coming unplugged inside the box.
Coated to protect against condensation: CC
Moving from the -50 oC storage temperature to room temperature would sometimes lead to condensation within the system, and this could short out the electronics. To prevent this, we added a protective conformal coating (CC) on the circuit board to protect against any condensation.
The customer was already using SAE24 threaded process connections, so we matched it.
Mismatched analog signals: CP, 5IN
Another customization for this device is a mismatched analog input and output: a 4-20 mA output pressure data (CP) and a 0-5 Vdc setpoint input signal (5IN). Typically customers use an input and output that match, but this customer needed a mismatched setup to make this pressure controller work with their existing system signals, including a PLC that has an output of 0-5Vdc.
Remote analog tare: GT
Because the customer was not using a digital interface for communications with the PLC, they needed a way to remotely tare the controller using analog signals. To satisfy this need, we designed this device to be tared by grounding Pin 1 of the M12 connector.
Preconfigured setpoint: PUSP: 0
To avoid revealing potentially sensitive information, this pressure controller will always bring up a setpoint of 0 PSIG (PUSP: 0).
Reference: click here.
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