Danfoss 060-216166 KP 37 Pressure Switch 4-21 bar G1/2

KP 37: a 4 to 21 bar pressure switch with G 1/2 connection for compressors and heating plant

Danfoss 060-216166 is a KP 37 from the KP/KPI family, the generation of switches whose data sheet describes them as used for control, monitoring and alarm systems across many industrial applications. The KP prefix means it is intended mainly for gaseous media. Its regulating window of 4 to 21 bar and fixed-width differential range of 1.8 to 3.0 bar place it between the low-pressure KP 35/36 types and the high-pressure units used on condensers, so it is typically chosen for compressed-air receivers, heat pump circuits and similar pressure bands.

The switch has a standard SPDT snap-action contact, an automatic reset and the simple G 1/2 male process thread that is easy to tap into a manifold. The enclosure is the IP30 version, so it belongs inside a cabinet, plant room or machine frame rather than outdoors.

Technical specifications

Range, differential and limits in practice

The 28 bar maximum working pressure sits well above the 21 bar upper end of the range, which leaves headroom for pressure peaks; the 32 bar test pressure is the value to respect for system leak testing. Because the differential is adjustable between 1.8 and 3.0 bar, a cut-in of 12 bar and a differential of 2.0 bar gives a cut-out at 10 bar. Choose the differential from the volume of the system: a small receiver needs the wider setting to avoid short cycling.

Danfoss also publishes this family with gold-plated contacts and with stainless-steel wetted parts for demineralised water, but those are different code numbers; this code is the standard silver-contact version. The data sheet lists a manual trip function for verifying the wiring without pressure and an optional manual reset variant.

Mounting, wiring and checks before ordering

Fit the switch with a flat sealing washer on the G 1/2 thread and tighten with a spanner on the hexagon, never by turning the housing. Electrical connection is made from the front, which makes rack mounting easier; use cable that suits the entry and keep conductors within the terminal range printed in the installation guide for the KP 34 to KP 37 types.

Before ordering, confirm the medium, the setting you need within 4 to 21 bar, the load on the contact and whether the cabinet needs more than IP30. Seven Star LLC is an independent supplier in Muscat and can quote this exact code; please state the quantity and delivery location.

Choosing the installation point on the pressure line

Connect the KP 37 to a point that sees the true system pressure rather than a local disturbance. On a compressed-air receiver, a tapping on the vessel or a nearby header is usually steadier than a point right after the compressor outlet, where pulsations are strongest. If the line pulsates or vibrates, use a short flexible or looped connection and support the switch on a bracket or panel so that the G 1/2 joint does not carry the weight and vibration on its own.

Where the medium may carry oil or condensate, mount the switch above the tapping so that liquid drains back into the line instead of collecting in the bellows. Fit an isolation valve where the system design allows, so the switch can be removed for checking without draining the whole system.

Setting and commissioning the switch

With the contact wired and the system at a safe low pressure, set the range to the required cut-in or cut-out point and the differential to suit the receiver volume, following the Danfoss setting instructions. The scales are a guide only; final settings should always be confirmed with a calibrated pressure gauge on the same line.

Raise and lower the pressure slowly through the switching points and note the readings at which the contact changes over. Adjust in small steps, repeat the test, and record the confirmed values on the panel drawing or a tag near the switch. The manual trip function described in the data sheet can be used to check that the control circuit responds before the system is pressurised.

Plant-room conditions in Oman and the GCC

The IP30 enclosure means the switch should be protected from water, wind-blown sand and direct sun. Compressor rooms in Oman can become very hot in summer, and the heat from the compressor itself adds to the room temperature, so ventilate the room well and keep the switch away from hot discharge pipes and exhaust air.

Fine dust settling inside an IP30 housing can affect the contact over time, especially in quarries, cement plants and desert sites. Mount the switch inside a cabinet or a covered area, close unused cable entries, and in humid coastal locations avoid positions where condensation from cold surfaces can drip onto it.

Periodic checks in service

Test the switching points against a reference gauge during routine maintenance and after any major work on the pressure system. Check the electrical connections for tightness and signs of overheating, inspect the process connection for leaks, and replace the switch if the set points drift repeatedly or the contact shows erratic behaviour.

Documents and quotation

The document is the Danfoss KP and KPI pressure switch data sheet (AI557543881535), unaltered, with the full ordering tables and dimensions. More controls are listed under pressure instrumentation. Ask for a quotation quoting 060-216166.