Skid System Accessories
Pressure Switches
Description
Pressure Switches are used to prevent over-pressurization of piping systems with positive displacement pumps. They are added to the pump’s discharge piping and set to open at a higher pressure than the typical system pressure but lower than the maximum pressure of any components or piping.
Pressure switches can be wired for normally open or normally closed depending on the desired connection to the pump, PLC, or SCADA system. Pressure switches are usually installed in combination with pressure relief valves and pressure gauges. Pressure gauges are typically required to help set or adjust the pressure trip value of the switch.
Application
Generally, pressure switches are recommended on most chemical feed systems. There are a few reasons:
- Protect the chemical feed pump from damage. Peristaltic pumps have tubes that can fail or fatigue quickly at higher pressures. Diaphragm pumps can suffer diaphragm failure or increased wear, or check valves seats/O-rings can become deformed and unseat. Pressure switches can signal alarms and automatically turn off pumps. (Pumps and motors may also have sensors that will automatically shut down the pump and stop chemical injection or processing, but may not activate until well after system damage has occurred.)
- Protect piping, tubing, and other ancillary components on the discharge side of the pump.
- They can be used in conjunction with a pressure gauge to identify closed valves or clogged injectors or other unusual pressure spikes.
Installation
Pressure switches should be installed close to the pump. They can easily be installed on a skid within a few feet of the pump discharge.
- Pressure switches should be installed in conjunction with a Gauge Guard to prevent chemical exposure to the switch.
- A pressure gauge is also required so the switch can be properly set to the correct pressure.
- A pressure switch is combined with a pressure relief valve to help relieve pressure after a high-pressure event.
Blue-White offers pressure switches as an option on skids. (Note that pressure relief valves are a standard component on all pump skids.) Pressure switches can be purchased separately and can be installed anywhere in the discharge piping. Pressure switches are watertight and have 316SS construction.
Wiring: Pressure switch includes 4 loose wires, 60” long. The single switch can be wired for normally open or normally closed contact.
Rating: 5 A @ 125/250 VAC, 5 A @ 28 VDC resistive, 3 A @ 28 Vdc inductive. Red = NC, White = C, Blue = NO, Green = Ground.
Pressure adjustment: Pressure switches are field adjustable at a range of either 10-100 psi, or 20-200 psi. The range of the switch will be indicated by the last numbers on the part number (200# = 200 psi). To adjust the range, pull down the outer ring to access dial. Turn the dial left or right to adjust the setting.
Ordering Information
Materials available: 316L Stainless Steel. Combine with Guage Guard for connection to PVC, CPVC, or PVDF piping.
Pressure ranges: 10-100 PSI, 20-200 PSI
Connection types: ¼ inch NPT connection to process or gauge guard.
Certifications: CE, UL, CSA, ROHS.
Pressure Switches
| Part number | Description | Material | Size (in) |
| 90018-037 | Pressure Switch, 10-100 psi range, ½” conduit connection, loose wires (60 in.) | 316SS | 0.25 |
| 90018-103 | Pressure Switch, 20-200 psi range, ½” conduit connection, loose wires (60 in.) | 316SS | 0.25 |
Gauge Guards
| Part number | Description | Material | Size (in) |
| 90008-746 | Gauge Guard, GGU050POTT, PTFE Diaphragm | PVC | 0.50 |
| 90008-768 | Gauge Guard, GGU050COTT, PTFE Diaphragm | CPVC | 0.50 |
| 90008-868 | Gauge Guard, GGU050KOTT, PTFE Diaphragm | PVDF | 0.50 |
