Square D / Pumptrol · Class 9013 Type FHG
9013FHG12J52
The single most common air compressor pressure switch in North America. Diaphragm actuated, contacts open on rising pressure, cut-out adjustable with a fixed differential. Sold bare (J52), with unloader (M1), with auto/off lever, and with a four-port manifold.
Specifications
- Action
- Standard — contacts open on rising pressure
- Adjustable range
- 70–150 psi adjustable on rising pressure (482.6–1034.2 kPa)
- Differential
- Approximately 30 psi fixed (206.8 kPa) (fixed)
- Factory settings
- Cut-in 95 psi / cut-out 125 psi as shipped
- Ports
- 1/4 in. NPSF internal (female) standard; optional four-port manifold for gauge, relief valve and unloader line
- Unloader
- Optional two-way relief (unloader) valve — bleeds head pressure at cut-out so the motor restarts unloaded
- Lever / disconnect
- Optional auto/off disconnect lever
- Enclosure
- NEMA 1 standard, NEMA 3R optional
- Temperature
- Ambient -22 °F to 257 °F; controlled air 32–158 °F
- Burst / destruction
- Destruction pressure 220 psi (1516.8 kPa) — this is not a working rating
Electrical
- 2 NC snap-action contacts, DPST-DB, Form YY — breaks both legs of a 240 V single-phase circuit
- Power-circuit rated: switches motor current directly on small single-phase motors
- Screw-clamp terminals, 10 AWG max
- Two 1/2 in. NPT conduit entries
- 50/60 Hz, UL Listed / CSA Certified, RoHS
Size against motor full-load amps with the motor amperage calculator, and check feeder sizing with the voltage drop calculator.
Adjustment
- Only one adjustment exists on FHG: the large centre range nut. Clockwise raises both cut-in and cut-out together.
- Roughly one full turn of the range nut moves the setting a few psi — go a half turn at a time and re-test.
- The differential is fixed by the mechanism. If you need a wider or narrower gap, you need a Type G or an adjustable-differential switch, not more turning.
- Never adjust cut-out above the tank data-plate MAWP, and leave 10–15 psi below the ASME relief valve setting.
Before you open the cover
Kill power at the disconnect and lock out. Bleed the tank to 0 psi. Never set cut-out above the tank data-plate MAWP. Verify your numbers first in the cut-in / cut-out calculator.
Best fit
- Single-phase shop recips through roughly 2 HP at 230 V
- Portable and contractor compressors with 95/125 psi duty
- Any job where you want a factory-set, drift-proof switch and don't need differential control
Watch out
- Continuous hiss from the unloader port while running means the unloader seat failed — replace the switch.
- Water inside the switch body cracks the nitrile diaphragm; mount the switch above the tank tapping where possible.
- The M4 option is a low-pressure cut-off, not a manifold: it latches OFF when tank pressure falls 10 psi below cut-in and needs a manual restart.
Cross-references
- Lefoo LF10-1H / LF10-L1 (form-fit replacement)
- Furnas 69MB7LY, 69JF7LY (functional equivalent, 95/125)
- Condor MDR2/11 (metric plumbing, adjustable differential)