Features/Benefits:
- Used to signal equipment when pressure in a piping system either rises or falls to a set pressure.
- Adjusts easily with adjusting screw.
- Maximum operating pressure of 150 psi via three easy-to-change spring ranges.
- NEMA 4X design and patented Fail-Dry® enhance system safety.
- Electrical switch is UL recognized and CSA approved.
- Corrosion-resistant plastic cord grip and 18" cable simplify installation.
- Better piston design and piston guidance vs. competition enhances reliability and accuracy.
- Tested to 1,000,000 cycles in laboratory conditions.
- PTFE diaphragm with no wetted metals or elastomers ideal for ultra-pure liquids.
- Versatile snap-action 16 Amp/3 terminal switch is standard; 25 Amp and low deadband 3 Amp switches optional.
How it Works:
The Plast-O-Matic Series SWT Pressure Switch can be used to activate or de-activate equipment when pressure in a piping system either rises or falls to a set pressure. Liquid in the piping system acts against a Viton-backed PTFE diaphragm (the Viton does not contact liquid). The diaphragm works against a piston and spring, which triggers an electrical switch within the upper chamber of the unit. Spring pressure is set by simply threading the adjusting screw in or out.
Series SWT contains a snap-action electric switch with three terminals. One is common, one is normally-open, and one is normally-closed. The normally-open switch will close upon reaching the set pressure, and the normally-closed switch will open when set pressure is reached. Set pressure can be reached by higher system pressure falling to the set value, or when lower system pressure rises to the set value.
As an example, the switch can be set to actuate at 50 psi, rising pressure (switch actuates when pressure rises to 50 psi). When the pressure rises to 50 psi the normally-open contact will close, and the normally-closed contact will open. Therefore, depending on how the switch is wired, a light, or a pump, etc. can be energized or de-energized...or one item could be energized and another de-energized at the same moment. As the pressure continues to rise, no further changes occur....
Hysteresis:
If and when the pressure decreases, the switch will reverse, but not at 50 psi. Because of hysteresis (also known as "deadband"), the reversal will occur at approximately 40% lower pressure.
Deadband helps to prevent oscillation or "hunting." In other words, without sufficient deadband, the switch will be actuating and de-actuating too often. For applications where it is critical to de-actuate with less deadband, a 3-amp switch is available. See specifications below.
Dimensions:
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