The KPH300 is a compact mechanical pressure switch that opens or closes an electrical circuit at a field adjustable pressure setpoint. It uses proven diaphragm or piston sensing technology, selected by measuring range, and covers switching ranges from -5 to -28 inches Hg through 450 to 4600 PSIG. Both the setpoint and the hysteresis are adjustable in the field, and the switch can also be factory set to a specified point. Its low cost and reliable snap-action switching make it well suited to OEM and industrial pressure switching applications.
Pressure Ranges and Switching
The KPH300 provides snap-action switching with adjustable hysteresis across a wide span, from -5 to -28 inches Hg vacuum through 450 to 4600 PSIG. Three model classes cover this span: KPH300V for vacuum, KPH300L for low pressures, and KPH300H for high pressures. Repeatability is typically plus or minus 2 percent of full scale range at 70 degrees F (21 degrees C).
Adjustable Setpoint and Hysteresis
Both the switching point and the hysteresis are adjustable in the field. The setpoint is set with a 2 mm hex wrench turned in the connector mounting boss, where clockwise rotation raises the setpoint over a typical range of about 10 to 12 turns. Hysteresis is set with a small slotted screwdriver near the ground terminal.
The switch can be factory set to a specified setpoint; the desired pressure and whether it acts on rising or falling pressure are specified with the order. Turning the hysteresis adjustment fully clockwise or counter-clockwise disables the switch function, and the adjustment screw should not be forced past its maximum or minimum point, which can damage the switch.
Sensing Element, Materials, and Seal Options
The KPH300 senses pressure with a diaphragm or piston element, chosen by range, using an NBR measuring element. Standard wetted materials are zinc-nickel plated steel and NBR, and the housing is zinc-nickel plated steel. The process connection is 1/4 inch NPT male, with other fittings available on request.
Optional diaphragm and wetted-material variants can be supplied for other media: 316 stainless steel wetted materials, an EPDM diaphragm rated -10 to 250 degrees F (-23 to 121 degrees C), an FKM diaphragm rated 0 to 250 degrees F (-18 to 121 degrees C), and a low-temperature nitrile (HNBR) diaphragm rated -40 to 110 degrees F (-40 to 43 degrees C). Some options carry a 10 piece minimum and are not available for all ranges.
Electrical Connections and Contact Rating
The KPH300 uses an SPDT micro-switch with a solid silver, self-cleaning contact rated 6 A at 125/250 VAC and 6 A at 12/24 VDC. The standard electrical connection is a DIN 43650 plug connector (Connection 8). An M12 x 1 four-pin connector (Connection 25) and a 3 foot integral cable (Connection 36) are also available.
Ingress protection is IP65 with the Hirschmann plug connector and IP67 with all other connections. The switch is CE compliant to suppress RFI, EMI, and ESD, and it is RoHS compliant. Maximum switching frequency is 100 cycles per minute, and rated service life is greater than 1,000,000 load cycles.
Temperature, Proof Pressure, and Physical Data
The KPH300 operates across a media, ambient, and storage temperature range of -4 to 176 degrees F (-20 to 80 degrees C) and weighs approximately 0.2 lb (0.09 kg). Proof pressure depends on the range: 350 PSIG for the vacuum model, 870 PSIG for the 3/7 through 30/290 ranges, and 5000 PSIG for the 100/220 through 450/4600 ranges.
- Switching ranges: -5 to -28 inches Hg through 450 to 4600 PSIG
- Switch type: snap-action SPDT with adjustable hysteresis
- Contact rating: 6 A at 125/250 VAC, 6 A at 12/24 VDC
- Process connection: 1/4 inch NPT male
- Wetted materials: zinc-nickel plated steel and NBR
- Ingress protection: IP65 (Hirschmann plug) or IP67 (all others)
- Weight: approximately 0.2 lb (0.09 kg)
Applications
The KPH300 is designed for pressure switching in hydraulic and pneumatic systems, pumps and compressors, tank monitoring, leak detection, and water management. Its combination of reliability and low cost also makes it well suited to many OEM applications that need a compact, field adjustable pressure switch.
Common Questions about KPH300 - Compact Pressure Switch
The KPH300 spans vacuum through high pressure, from -5 to -28 inches Hg up to 450 to 4600 PSIG. The vacuum version is the KPH300V. Low-pressure versions are the KPH300L, from 3 to 7 PSIG through 30 to 290 PSIG. High-pressure versions are the KPH300H, from 100 to 220 PSIG through 450 to 4600 PSIG.
The switchpoint uses a 2 mm hex wrench in the connector mounting boss, and clockwise turns raise it over roughly 10 to 12 turns of range. Hysteresis is adjusted with a small flat-blade screwdriver at the access hole beside the ground terminal. Turning the hysteresis screw fully in either direction disables switching, and forcing either screw past its limit can cause damage.
Three connections are offered: a DIN 43650 plug (Connection 8, standard), an M12 x 1 four-pin connector (Connection 25), and a 3 foot integral cable (Connection 36). On the DIN plug, terminal 1 is common, 2 is normally open, and 3 is normally closed. On the cable, black is common, brown is normally open, blue is normally closed, and green is ground.
It uses a single-pole double-throw (SPDT) snap-action micro-switch. The contact is solid silver with a self-cleaning action and carries 6 A at 125/250 VAC or 6 A at 12/24 VDC. Cycling can run up to 100 times per minute, and it is rated for more than one million load cycles.
Its standard construction pairs an NBR seal with zinc-nickel plated steel for both the wetted parts and the housing. When a different elastomer is needed, the diaphragm can be specified as EPDM (-10 to 250 degrees F), FKM (0 to 250 degrees F), or low-temperature HNBR nitrile (-40 to 110 degrees F), and a 316 stainless steel wetted-materials option is available. Some options need a 10 piece minimum.
The standard unit operates from -4 to 176 degrees F (-20 to 80 degrees C) for media, ambient, and storage. Ingress protection is IP65 when the Hirschmann DIN plug is fitted and IP67 with the M12 connector or the integral cable. It carries CE compliance for RFI, EMI, and ESD suppression and meets RoHS.
Order codes list model, switch, fitting, range, electrical connection, then options, as in KPH300L-3 2 15/200 8 SP. Switch 3 is SPDT and fitting 2 is 1/4 inch NPT male. Connections 8, 25, and 36 are the DIN plug, M12, and cable. Options include C, SP, SS, EP, VT, and HNBR, and not all suit every range.
The maximum overpressure varies by the selected range. The vacuum model tolerates 350 PSIG. Ranges from 3 to 7 through 30 to 290 PSIG tolerate 870 PSIG, and ranges from 100 to 220 through 450 to 4600 PSIG tolerate 5000 PSIG. Proof pressure defines this overpressure limit for each version.
Product Specifications
Ranges
-5...-28 Hg to 450...4600 PSIG
Wetted Materials
Zinc-Nickel Plated Steel and NBR
Media Temperature Range
-4...176 °F (80 °C)
Product Features
CE Compliant to Suppress RFI, EMI, and ESD
Field Adjustable Setpoint
Diaphragm or Piston Type Sensing Element
Documents
Software Downloads
There are no downloads to display at this time. If you think this is incorrect, please contact us and let us know the issue you are having.
Videos
There are no videos to display at this time. If you think this is incorrect, please contact us and let us know the issue you are having.
Accessories
There are no accessories to display at this time. If you think this is incorrect, please contact us and let us know the issue you are having.