WIKA A2G-55 Eco Differential Pressure Transmitter, 250-5000 Pa

WIKA A2G-55 Eco differential pressure transmitter for air and clean gases

The WIKA A2G-55 is a compact differential pressure transmitter for very low pressures in ventilation, air-conditioning, laboratory and clean room applications. It is based on a piezoresistive measuring cell, offers eight fixed ranges from 0 … 250 Pa up to 0 … 5,000 Pa, and gives a 0 … 10 V output as standard, with 4 … 20 mA as an option. WIKA describes it as an Eco version, offering good performance at an attractive price, intended for detecting small air flows and measuring low pressures of air and non-aggressive gases. Seven Star LLC supplies the A2G-55 in Oman and the GCC as an independent supplier in Muscat, and this page explains the ranges, outputs and mounting so that an RFQ can state them precisely.

What the A2G-55 measures

Differential pressure is the difference between two pressures, here on the order of tens to thousands of pascals. In an air handling unit that difference across a filter rises as the filter loads with dust, and the difference across a fan or duct section can indicate air flow. In a clean room or laboratory, a small positive or negative pressure relative to the surrounding area keeps contamination out or in. The A2G-55 senses these small differences with a silicon piezoresistive cell and converts them to a proportional electrical output that building automation or a controller can read. The data sheet lists applications of measuring differential and static pressures, filter monitoring and overpressure monitoring in clean rooms and laboratories.

Technical specifications of the A2G-55

Outputs and wiring of the A2G-55

The standard 0 … 10 V version is wired with three conductors: pin 1 supply (+), pin 2 output signal and pin 3 ground. The optional 4 … 20 mA version is a two-wire loop using pin 1 as loop plus and pin 3 as loop minus. The supply for the voltage version is DC 13 to 32 V, and the optional AC supply makes it easier to power from a building 24 V AC transformer, which is common in HVAC systems. The wiring enters through an M16 cable gland to screw terminals up to 1.5 mm². Because the signal range matches standard building automation inputs, no signal converter is needed.

The pressure ranges are fixed and cannot be changed after delivery, so the range must be specified at ordering. Choose a range so that the normal working value is between roughly a third and two thirds of full scale; a range chosen too wide wastes the available resolution, and one chosen too narrow will saturate when a filter blocks.

Where the A2G-55 fits and related WIKA models

The data sheet names the A2G-50 as a similar transmitter on a separate data sheet. For on/off control of the same quantity, WIKA offers the A2G-40 differential pressure switch with six adjustable range increments. The A2G-55 is a plain transmitter, so it provides a continuous reading, and the A2G-40 provides alarm contacts. Where the application needs higher pressures, liquid media, or hazardous-area approval, a different instrument family is required, for example the 732.51 differential pressure gauge or industrial transmitters such as the S-20.

Selection and ordering checklist for the A2G-55

• Measuring range from the eight fixed options, with a margin above the normal working pressure.
• Output: 0 … 10 V (standard) or 4 … 20 mA (optional).
• Supply: DC 13 … 32 V or optional AC 13 … 32 V.
• Hose size: the process connection suits 5.5 mm inner diameter; measuring hoses (PVC or silicone, 4 mm or 6 mm) and duct connectors are WIKA accessories.
• Ambient and medium temperature within -10 … +50 °C.
• Medium: air or clean, non-aggressive gas only.
• Approvals such as EAC if required.

Installation and commissioning of the A2G-55

Mount the transmitter on a wall in a vertical position. Connect the high-pressure tube to the plus connection and the low-pressure tube to the minus connection, using hoses of 4 or 6 mm inner diameter that fit the 5.5 mm nozzle, and keep them short, free of kinks and without liquid traps. Take the pressure through duct connectors that face away from the flow, so that dynamic pressure is not added to the reading. After powering, check the zero reading with both ports open to the same air and then compare against a manometer. Because the accuracy is ±2.5 % of full scale, check your control tolerance before choosing a narrow range. The device is maintenance-free, but the hoses and duct connectors should be inspected for blockage or cracking.

Typical applications in Oman and the GCC

In Oman and the Gulf the A2G-55 is used in air handling units for filter monitoring in hospitals, data centres, laboratories, pharmaceutical suites and clean rooms, and in building management systems that show filter loading in the face of high dust levels. Dust and sand quickly load outdoor-air filters, so a continuous measurement shows the right moment to change filters. The IP65 rating allows outdoor wall mounting within the specified -10 to +50 °C, though sun-exposed enclosures should be checked against the upper limit.

A2G-55 ranges and typical use

Information to send with an RFQ

• A2G-55 with range in Pa
• Output signal and supply
• Hoses and duct connectors needed
• Quantity and delivery site

Documents and quotation

The WIKA data sheet for the A2G-55 is attached on this page.

Send the range, output and quantity and Seven Star LLC will confirm availability and a quotation.