Dwyer Magnesense AT-MSX Manual, Specifications and Replacement Options

The Dwyer Series AT-MSX is the ATEX/IECEx approved version of the Magnesense® MSX differential pressure transmitter, built into a flameproof aluminium enclosure for monitoring pressure and air velocity in hazardous areas. It suits duct, room and building pressure, filter monitoring and clean room pressure with the signal sent back to a control room. Dwyer publishes it as a one-page datasheet rather than a full manual. That datasheet is below, with the key figures, setup notes and where to buy it.

Download the AT-MSX Manual (Datasheet)

Download the Dwyer Series AT-MSX Magnesense® Datasheet (PDF)

Document type: Dwyer product datasheet, one page. No revision or date is printed on it. It covers features, applications, specifications, the model code chart, pressure limits by port and valve option, and dimensions. It does not include a wiring diagram or a fault code list.

AT-MSX Specifications

All figures below are taken from the Dwyer Series AT-MSX datasheet.

AT-MSX Setup and Commissioning Notes

The datasheet has no fault codes or troubleshooting steps, so these notes come from its specification content. Check them before you commission the transmitter or when the reading doesn't look right.

Choose the output and power wiring

For a 4 to 20 mA signal, wire it 2-wire on 10 to 36 VDC, with a total loop resistance of 0 to 1250 Ω max. For a voltage signal, wire it 3-wire on 17 to 36 VDC or isolated 21.6 to 33 VAC, then select 0 to 10 V or 0 to 5 V. The voltage output needs a minimum load resistance of 1 kΩ. Current consumption is 21 mA max continuous.

Set the range and units

Ranges are field selectable in English or metric units. The model code sets the full scale (125, 250, 1250 or 7000 Pa), whether it is uni-directional or bi-directional, and whether it reads in in w.c., Pa or mm w.c. Zero and span are set with digital push-buttons. A square root output can be selected for pitot tubes and similar flow sensors.

Allow for dampening and flame arrestor delay

Response is instantaneous by default, or 3 s when dampening is selected. On top of that, the Exd flame arrestors slow the reading: up to 30 s from full scale to zero with standard pressure ports, depending on model and range, and about 15 s with LD pressure ports on very low ranges. A slow reading during commissioning may be this delay rather than a fault.

Stay inside the pressure limits

Maximum pressure depends on the port and valve option. VS0: 10 kPa with one port or both ports connected. VS1: 20 kPa with one port, 15 kPa with both. VS2: 40 kPa with one port, 20 kPa with both. Service is air and non-combustible, compatible gases only.

Mounting and cable entry

Mounting orientation does not affect the pressure measurement. The two 1/2 inch NPT female cable entries come without cable glands, so supply them separately. The process connections are 1/8 inch NPT female, with high and low pressure ports marked on the dimension drawing.

Buy the AT-MSX

Controls Traders lists the ATEX/IECEx Approved Magnesense® Differential Pressure Transmitter (SKU AT-102NA-MSX-20-PA-LCD-W1). Using the datasheet model chart, that code is the aluminium AT enclosure, bi-directional, the 125 Pa range in Pascals, with LCD and a glass window cover. The product page shows current availability. As an authorised Dwyer distributor, we can also help you confirm a different range or port option.

Related Dwyer MSX Options

• Dwyer Selectable Air Differential Pressure Sensor with Universal Output (SKU MSX-WXX): the standard MSX for non-hazardous areas such as AHU filters, duct static pressure, clean rooms and VAV air flow.
• Field Upgradeable Display for MSX / MSXP (SKU A-MSX-LCD): adds an LCD to a standard MSX or MSXP. Contact us before ordering it for an AT-MSX.
• Dwyer Air Differential Pressure Switch, Explosion Rated (SKU AT-101NA-ADPS-08-2-N-B1VS): the Series AT-ADPS ATEX/IECEx approved switch, for when a hazardous area job needs a switched alarm rather than an analogue signal.

For other pressure, temperature and humidity sensors, browse our sensors and transducers or the full Dwyer range. For help choosing between sensor types, read our differential pressure sensor selection guide.