Johnson Controls P499 Electronic Pressure Transducer (PENN)

Overview

The Johnson Controls P499 is a series of compact, rugged, direct-mount electronic pressure transducers sold under the Johnson Controls PENN brand. Designed for commercial refrigeration and air conditioning, the transducers produce an analog signal proportional to sensed pressure and feed it to chiller controllers, condensing unit controls, fan speed controllers and building automation systems. Their defining feature is a pressure port machined from a single piece of 17-4PH stainless steel, so no O-rings, organic materials or welds are exposed to the media. That gives a leak-proof, all-metal sealed pressure system that resists refrigerant loss, vibration, pressure pulsation and freeze-thaw cycles on suction lines.

Seven Star LLC supplies the Johnson Controls P499 to HVAC and refrigeration contractors, chiller service companies, cold store operators and OEM panel builders across Oman and the GCC. From our Muscat office we help identify the correct product code from an existing nameplate, match the output signal to the controller and supply the wire harness that the transducer needs.

Measurement Principle

Pressure applied to the Johnson Controls P499 acts on a stainless steel diaphragm. A piezoresistive strain gauge is bonded to this diaphragm with high-temperature glass, so as the diaphragm deflects under pressure the gauge resistance changes in proportion. An application-specific integrated circuit (ASIC) conditions and amplifies this small signal, applies digital compensation for temperature, and produces an output that varies in direct linear proportion to pressure. Because compensation is digital, the transducer holds its accuracy across wide ambient swings, high humidity, condensation and icing, which are typical at outdoor condensing units in the Gulf summer and on refrigerated suction lines.

The ratiometric Johnson Controls P499 receives a nominal 5 VDC supply and gives an output of 10 to 90 percent of that supply, which is 0.5 to 4.5 VDC nominal; the controller compares output with its own supply so small supply variations cancel out. The 0 to 10 VDC and 4 to 20 mA versions run from a wider 12 to 30 VDC or 9 to 30 VDC supply and suit longer cable runs to a building management system. The bulletin gives simple equations to check output against a reference gauge in the field.

Engineering Design of the Johnson Controls P499

The Johnson Controls P499 has a slender body that accepts deep-socket wrenches and needs zero turning radius, which helps on crowded compressor racks. Two direct-mount pressure connections are standard: a 1/4 in. SAE 45 degree flare internal thread (7/16-20 UNF) with Schrader valve depressor, known as Style 47, and a 1/8-27 NPT external thread, known as Style 49. Electrical connection is through a Packard connector of 40 percent glass-filled polyetherimide, and models without an integral cable use separate WHA-PKD3 wire harnesses in 2 m, 4 m and 6 m lengths.

The Johnson Controls P499 withstands vibration of 20 g from 20 to 200 Hz and shock of 200 g for 11 ms, and its electronics are environmentally protected for operation from minus 40 to 85 degrees Celsius at 0 to 100 percent relative humidity. It is UL Listed, UL Recognized for Class I, Division 2 hazardous locations, CE marked and C-Tick compliant. For the Johnson Controls P499, the manufacturer notes that 316L stainless steel construction and ranges up to 1,764 psi (120 bar) are available on request for high-volume orders with specific application requirements.

Key Features

The technical bulletin highlights these features of the Johnson Controls P499 series.

• Single-piece machined 17-4PH stainless steel pressure port with no O-rings or welds in contact with the media.
• Compatibility with ammonia, most refrigerants, water, condensate, carbon dioxide, glycol and other media suited to 17-4PH.
• Environmentally protected, digitally compensated electronics for freeze-thaw and high-humidity duty.
• Five pressure ranges from -10 to 100 psi up to 0 to 750 psi.
• Output options of 0.5 to 4.5 VDC ratiometric, 0 to 10 VDC or 4 to 20 mA.
• Accuracy of plus or minus 1 percent full span and linearity of plus or minus 0.25 percent full span.
• Slender body with Style 47 flare or Style 49 NPT direct-mount fittings.
• UL, CE and C-Tick listings, with UL recognition for Class I, Division 2 hazardous locations.

Industrial Applications

Typical applications named by Johnson Controls include HVAC and refrigeration, chillers, fan speed controls, pumps and compressors, agricultural applications and industrial process control. In Oman these map directly onto air-cooled chillers serving malls, hospitals and hotels in Muscat, packaged rooftop units, cold stores and food distribution centres in Sohar and Salalah, and ammonia refrigeration in fish processing and dairy plants. A Johnson Controls P499 on the condenser line can drive head pressure control of condenser fans, while a transducer on the suction line feeds capacity control and low-pressure protection.

Because the series is used by many equipment manufacturers, service teams across the GCC often need a direct replacement with the same range, output and fitting. Seven Star LLC supplies every Johnson Controls P499 range with the matching harnesses, and our Muscat engineers cross-check product codes and controller input requirements to make replacement straightforward.

Technical Specifications

The following Johnson Controls P499 data comes from the PENN product/technical bulletin LIT-12011190.

How to Order

To request a quotation for the Johnson Controls P499, send Seven Star LLC the product code from the transducer label, or the required range, output and fitting style, together with the harness length. Our Muscat instrumentation division confirms availability, shares the Johnson Controls technical bulletin and supports refrigeration engineers in Oman and the GCC. Other pressure instruments we supply include the Rosemount 2051 pressure transmitter, the Dungs GW A6 compact pressure switch and the Dwyer Photohelic 3000MR differential pressure switch gauge.