Series-AP

Supported Applications

The Dwyer Series AP Diaphragm Operated Pressure Switches are designed for instrument air or other low-pressure applications. These switches provide visible set points and external adjustment, making them suitable for monitoring pressure in systems handling air, non-corrosive gas, or liquid service compatible with the wetted parts.

Operating Conditions & Performance

The series operates within an ambient temperature range of -30 to 150°F (-35 to 66°C). Measurement ranges span from vacuum and low differential pressure up to higher gauge pressures, specifically:

• 10" vac-50 in w.c. (250 mm vac-1250 mm w.c.)
• 1-30 psig (0.07-2.1 bar)
• 10-125 psig (0.7-8.6 bar)

Maximum operating pressures vary by range, with values such as 15 psig (1.0 bar) for the vacuum/low-pressure ranges and up to 160 psig (11 bar) for the highest pressure configuration. Switch deadbands are defined per model; for example, Range Number 37 lists a low deadband of 0.4 psig (0.03 bar) and high deadband of 0.75 psig (0.05 bar) for mercury switch models.

Configuration Options

The Series AP offers configurable options across housings, switching mechanisms, wetted materials, and electrical ratings to accommodate specific installation needs.

Housing & Enclosure Options

• General purpose enclosure (NEMA-1)
• Weather-proof enclosure with condensate drain (NEMA-2, 3R)
• Explosion-proof enclosure (NEMA-7, 9; Class I Group C & D; Class II Group E, F & G)

Switching Mechanisms & Electrical Ratings

The series supports SPDT mercury switches and SPDT snap acting switches. Other switch types are available.

• Mercury Switch: 4A @ 120 VAC/DC, 2A @ 240 VAC/DC
• Snap Switch: 15A @ 120 VAC, 8A @ 240VAC, 0.5A @ 120 VDC, 0.25A @ 240 VDC

Note: Mercury switch units are not CE approved.

Wetted Materials & Connections

• Standard: Nylon reinforced Buna-N and steel
• Optional: PTFE covered diaphragm with 316 SS pressure port; Plated steel pressure port options available.
• Process Connection: 1/4" female NPT
• Electrical Connections: Screw terminal with a 7/8" (22.23 mm) hole for 1/2" (12.7 mm) conduit hub.

Key Product Differences

Variants within the series are distinguished by switch type, range number, and housing configuration. Mercury switch models require vertical mounting orientation, whereas snap switch models can be mounted in any position. Model numbers follow a structure indicating construction, reset options, housing, circuit (switching) options, wetted materials, and adjustable pressure ranges.

Specific model examples include:

• AP-153-33: Mercury switch, range 10 in VAC to 50 in w.c. (2.5 to 12.4 kPa), max pressure 15 psig (1.0 bar).
• AP-7021-153-33: Snap switch, range 10 in VAC to 50 in w.c. (2.5 to 12.4 kPa), max pressure 15 psig (1.0 bar).
• APF Series: Factory Mutual approved configurations available for specific ranges and circuits.