Sanhua PSV16AAL-S51 Dual Pressure Switch – LP −0.5~7 Bar / HP 8~42 Bar, Automatic Reset on Both Sides, 7/16" Flare

Sanhua PSV16AAL-S51 is a dual pressure switch (pressurestat) that protects the compressor in refrigeration and air conditioning circuits against both excessively low suction pressure and excessively high discharge pressure. A single body contains two independent pressure units.

Automatic Reset on Both Sides: The System Restarts by Itself When Pressure Returns to Normal

In this model both pressure units have automatic reset:

• Low pressure (LP) → AUTOMATIC reset: when the suction pressure returns to normal, the compressor switches on by itself.
• High pressure (HP) → AUTOMATIC reset: when the discharge pressure drops, the contact closes by itself; no manual intervention is required.

This behavior suits systems that must run continuously and have no operator on hand: cold rooms at remote locations, supermarket display cases, units operating automatically. When the pressure rises and falls for a temporary reason, the system recovers by itself and there is no need to call a service technician.

🔎 Which model should I choose? A version of the same pressure range with MANUAL reset on the high pressure side is also available in our catalog (PSV16AML-S51). If you want every high pressure trip to be noticed and investigated, choose the manual reset model; if you want the system to continue by itself, choose this automatic reset model. For lower-pressure circuits, the PSV15 (HP 6~32 bar) version is more suitable.

Technical Specifications (Official Sanhua Datasheet)

• Model: Sanhua PSV16AAL-S51 | Sanhua part no: 10660018602
• Low Pressure (LP): setting −0.5 … 7 bar · differential 0.7 … 5 bar (adjustable) · reset automatic
• High Pressure (HP): setting 8 … 42 bar · differential 5 bar (fixed) · reset automatic
• Contact: SPDT | Contact Rating: AC1 16 A / 400 V · AC3 16 A / 400 V · AC15 10 A / 400 V · DC 16 A / 24 V
• Connection: 7/16-20 UNF flare (with flare nut) — two
• Max. Working Pressure: HP side 4.5 MPa (45 bar) · LP side 1.65 MPa (16.5 bar)
• Medium Temperature: −40 … +120 °C | Ambient Temperature: −30 … +65 °C | Humidity: 0-95% RH
• Protection Class: IP30 (IP44 optional)
• Dimensions: body 123 × 63 mm · port spacing 33 ± 1 / 50 ± 1 mm · 4 × M4 mounting holes — official dimension drawing in the 2nd image
• Compatible Refrigerants: R22, R134a, R404A/R507, R407A/F, R407C, R410A, R448A/R449A, R450A, R452A, R513A
• Certificates: CE (LVD 2014/35/EU · EN 60730-1, EN 60730-2-6) · UL 508 (E480941)

• 🔧 Code breakdown: PSV = pressure control · 16 = dual (LP −0.5~7 / HP 8~42 bar) · A = LP reset automatic · A = HP reset automatic · L = flare connection. The solder connection version ends with the letter H, the capillary tube version with M.
• ⚠️ This variant (S51) is not certified to PED 2014/68/EU (EN 12263). For projects that require a certified safety switch under the Pressure Equipment Directive, the -S01 variant should be selected (HP differential 6 instead of 5 bar).
• There is no approval in the standard list for A2L/A3 refrigerants such as R32, R290, R717 and R1234yf; for these refrigerants, model-specific confirmation from the manufacturer is required.
• When setting, keep the HP cut-out value below the system design pressure and the safety relief valve setting; select the LP cut-out value according to the evaporator design temperature.
• Do not overtighten the flare connection; applying a drop of refrigeration oil to the flare nut face improves leak tightness.