The BAPI BA/APSW6-65 is part of BAPI's BA/APSW Adjustable Pressure Switch family - a precision dial-adjustable differential pressure switch designed for monitoring overpressure, vacuum, and differential pressure of air or non-combustible, non-aggressive gases. Configured for a field-adjustable range of 4-20 inWC (1000-5000 Pa) with +/-1% accuracy (minimum +/-0.02 inWC / +/-5 Pa).
The round body houses an SPDT Form C silver contact, an internal silicone diaphragm (tempered at 200 deg C for long-term stability), and a field-adjustable dial that selects any trip value within the specified range. The IP65-rated sealed against dust ingress and water jets - suitable for outdoor and wash-down adjacent installations. Rated for over 1,000,000 switching operations - among the highest cycle ratings in the industry. M20 cable conduit accepts standard 0.25-0.375 inch (6.5-9.5 mm) cable; both 1/4 inch spade plugs (AMP/DIN 46244) and push-on screw terminals are included for wiring flexibility. Made in USA by BAPI in Gays Mills, Wisconsin.
This switch is best suited for higher-range industrial and process monitoring: high-static AHU monitoring, dust-collector pressure-drop alarms, kiln/oven differential verification, and process-control interlocks where the trip point exceeds 10 inWC. The IP65 enclosure makes this SKU well-suited for outdoor rooftop installations, wash-down adjacent environments, outdoor commercial kitchens, and any application where weather exposure or occasional water-jet cleaning is possible. The +/-1% accuracy class on this SKU is preferred for spec-engineer documentation and applications where tighter set-point repeatability matters. Per BAPI's published applications: monitoring air filters and fan status, industrial cooling-air circuits, ventilation duct flows, and air flow proving for heater control or frost-prevention circuits.
Key Features
A field-adjustable dial on the round body selects any trip value within the 4-20 inWC (1000-5000 Pa) range. Setpoint adjustment is straightforward: remove the cover, turn the dial to the desired trip pressure (verified against a manometer if required), replace and secure the cover, and operate. No spring swap, no special tools - just a standard screwdriver to adjust the dial position. Accuracy is +/-1% (minimum +/-0.02 inWC / +/-5 Pa).
IP65-rated - dust-tight and protected against water jets from any direction. Suitable for outdoor rooftop installations, wash-down adjacent environments (commercial kitchens, food processing), and outdoor HVAC equipment monitoring. The cover seals against an internal gasket and is secured with cover screws. Body and cover are UV-resistant plastic for long-term outdoor stability.
Mechanical working life of over 1,000,000 switching operations - among the highest cycle ratings in the industry for HVAC pressure switches. Well-suited for applications with frequent cycling: filter alarms that trip and clear daily, intermittent fan-status verification, demand-controlled ventilation interlocks, and any process where the switch sees high duty-cycle action.
A SPDT Form C contact with three poles: 3 (COM), 2 (NO), and 1 (NC). When pressure rises above the trip point, COM (3) closes to NO (2); when pressure falls below the trip point, COM (3) closes to NC (1). Same SKU wires for either prove flow or prove no flow logic depending on which contact pair you use.
Versatile contact rating across multiple voltage classes: 0.4A inductive / 1.5A resistive at 250 VAC, 0.8A inductive / 3A resistive at 125 VAC, plus DC ratings of 0.4A at 30 VDC and 0.1A at 24 VDC. This combination of AC and DC ratings makes the BA/APSW suitable for BAS controller inputs, 24 VDC PLC inputs, interposing relays at 120/240 VAC, and panel indicator lights.
Silicone diaphragm tempered at 392 deg F (200 deg C) - free of gas emissions and dimensionally stable across the full operating temperature range. The tempering process eliminates outgassing that would otherwise cause drift in sealed-system applications and provides excellent long-term repeatability in pulsating-pressure environments.
Two plastic pipe connection pieces (external diameter 0.24 inch / 6 mm) - marked P1 (+) for higher pressure and P2 (-) for lower pressure. Push-on flexible tubing for fast installation; BAPI offers the BA/APSW-ACC accessory kit with 2 total pressure tubes and 2 meters of pressure tubing for in-duct mounting.
Both wiring methods are included: 1/4 inch (6.3 x 0.8 mm) AMP-style spade plugs in accordance with DIN 46244 for fast quick-disconnect work, plus push-on screw terminals for permanent installations. Cable enters through an M20 cable conduit that accepts 0.25-0.375 inch (6.5-9.5 mm) OD cable; a liquid-tight fitting is included.
Burst pressure rated 40 inWC (10 kPa) across the full BA/APSW family - even on the lowest-range variants. Tolerates transient pressure spikes from duct damper slams, fan starts, and commissioning test pressures without diaphragm damage. Operating temperature range: -4 to 185 deg F (-20 to 85 deg C).
BA/APSW Range Selection Guide
IP65 enclosure (sealed for outdoor / wash-down adjacent use). All BA/APSW variants share identical mechanical, electrical, and cycle-life specifications - they differ only in pressure range and accuracy class. Note that APSW1 and APSW4 have +/-5% accuracy, APSW2 has +/-2.5%, and APSW3, APSW5, APSW6 have +/-1% - if accuracy matters more than range fit, prefer the +/-1% models whose range bracket includes your set point. Both IP54 (base) and IP65 (-65 suffix) versions are available, plus EU-market variants (-EU and -65-EU) on models 1, 2, and 3.
| Model (Same Variant) | Range | Accuracy |
|---|---|---|
| BA/APSW1-65 | 0.08-1.2 inWC (20-300 Pa) | +/-5% |
| BA/APSW2-65 | 0.2-2 inWC (50-500 Pa) | +/-2.5% |
| BA/APSW3-65 | 0.8-4 inWC (200-1000 Pa) | +/-1% |
| BA/APSW4-65 | 0.12-1.6 inWC (30-400 Pa) | +/-5% |
| BA/APSW5-65 | 2-10 inWC (500-2500 Pa) | +/-1% |
| BA/APSW6-65 ← this SKU | 4-20 inWC (1000-5000 Pa) | +/-1% |
Technical Specifications
| Specification | Detail |
|---|---|
| Product Type | Adjustable differential pressure switch (round body, dial-adjustable) |
| Adjustable Setpoint Range | 4-20 inWC (1000-5000 Pa) |
| Accuracy / Deviation | +/-1% (minimum +/-0.02 inWC (+/-5 Pa)) |
| Drift | <=+/-15% over service life |
| Contact Arrangement | SPDT Form C (3-COM, 2-NO, 1-NC); silver contacts |
| Contact (Load) Rating | 0.4A inductive / 1.5A resistive at 250 VAC; 0.8A inductive / 3A resistive at 125 VAC; 0.4A at 30 VDC; 0.1A at 24 VDC |
| Reset Style | Automatic |
| Mechanical Working Life | Over 1,000,000 switching operations |
| Measurement Media | Air, non-combustible and non-aggressive gases |
| Diaphragm | Silicone, tempered at 392 deg F (200 deg C), gas-emission free |
| Burst Pressure | 40 inWC (10 kPa) - all ranges |
| Operating Temperature | -4 to 185 deg F (-20 to 85 deg C) |
| Storage Temperature | -40 to 185 deg F (-40 to 85 deg C) |
| Pressure Connections | 2 plastic pipe connection pieces, external diameter 0.24 in (6 mm); P1 (+) to higher pressure, P2 (-) to lower pressure |
| Body and Cover Material | UV-resistant plastic |
| Enclosure Rating | IP65 |
| Mounting | Vertical preferred (pressure connections pointing downward to drain condensate); horizontal mounting valid if no condensate forms but adds approximately 0.08 inWC (20 Pa) offset |
| Mounting Hole Spacing | 2.56 x 2.56 in (65 x 65 mm), 0.17 in (4.3 mm) holes; #8 screws supplied |
| Electrical Connections | 1/4 in (6.3 x 0.8 mm) AMP-style spade plug per DIN 46244 (included); push-on screw terminals also included; liquid-tight cable fitting included |
| Cable Conduit | M20 threads, accepts 0.25-0.375 in (6.5-9.5 mm) OD cable |
| Agency Approvals | CE (Low Voltage Directive 2014/35/EU; RoHS Directive 2011/65/EU) |
| Dimensions | Diameter 3.35 in (85 mm), depth 2.26 in (57.5 mm); with pressure connections: 4.00 x 2.32 in (101.5 x 59 mm) |
| Manufacturer | BAPI (Building Automation Products, Inc.) - Gays Mills, WI USA |
| Manufacturer Part Number | BA/APSW6-65 |
| Warranty | 5-Year BAPI Limited Warranty |
What's In the Box
- BAPI BA/APSW Adjustable Pressure Switch
- Cover (with sealing gasket for IP65 rating)
- Cover screws
- Mounting feet hardware (#8 screws supplied)
- Liquid-tight cable fitting (for M20 conduit)
- 1/4 inch spade connectors (AMP-style, DIN 46244)
- Push-on screw terminals
- Installation & Operation Instructions (BAPI doc 42074_ins_APSW)
- BA/APSW-ACC - BAPI's accessory kit with 2 total pressure tubes and 2 meters of pressure tubing (the BAPI-recommended pickup accessory for in-duct installations)
- Alternative pressure probes: ZPS-ACC01 (static pressure pickup port, wall-mounted), ZPS-ACC07 (static pressure probe, in-duct), ZPS-ACC11 or ZPS-ACC12 (pitot tube assemblies, for airflow proving)
- Cable for wiring (0.25-0.375 in OD compatible with M20 conduit fitting)
- Manometer for setpoint verification during commissioning
Documentation
Frequently Asked Questions
What is the BA/APSW6-65 used for?
The BA/APSW6-65 is a BAPI adjustable differential pressure switch for monitoring overpressure, vacuum, or differential pressure of air and non-combustible, non-aggressive gases. Used in HVAC and Energy Management applications including air filter and fan status monitoring, industrial cooling-air circuit monitoring, ventilation duct flow monitoring, and air-flow proving for heater control or frost-prevention circuits. The SPDT Form C contact closes (or opens) when the differential pressure crosses the dial-set trip point. This SKU is field-adjustable across 4-20 inWC (1000-5000 Pa) with +/-1% accuracy.
How do I adjust the setpoint?
Remove power before adjusting. Remove the cover, then use a screwdriver to turn the adjustment dial to your desired trip pressure on the scale. Replace the cover, push down until it latches, and secure with the cover screw(s). Do not operate the system with the housing open. Verify the trip point by slowly increasing and decreasing pressure with a manometer connected to the high port - a digital manometer is recommended for the +/-1% accuracy variants. Repeat the dial adjustment if needed. The dial scale is calibrated; small final adjustments may be needed to match your exact required set point.
What's the difference between IP54 and IP65 (this SKU)?
IP65 (this SKU): dust-tight (no dust ingress at all) and protected against water jets from any direction - suitable for outdoor rooftop installations, wash-down adjacent environments, outdoor commercial kitchens, and any application where the switch may be subjected to weather or occasional water-jet cleaning. IP54 (the base model without -65 suffix): protected against falling dust and water splash from any direction - suitable for indoor mechanical-room or panel-mount installations only. Specs are otherwise identical between the two variants.
What accuracy does this SKU deliver?
+/-1% deviation, minimum +/-0.02 inWC (+/-5 Pa). Drift is <=+/-15% over the service life. The accuracy class varies by base model: APSW1 and APSW4 are +/-5% (general-purpose monitoring), APSW2 is +/-2.5%, and APSW3, APSW5, and APSW6 are +/-1% (precision applications, spec-engineer documentation, regulated environments). The accuracy minimums apply at the lower end of each range; absolute accuracy improves as you approach mid-range and full-scale.
How do I wire the SPDT Form C contact?
The Form C contact has three poles inside the unit: 3 (COM, common), 2 (NO, normally open), and 1 (NC, normally closed). Use a three-conductor cable if you need all three terminals; a two-conductor cable if only one switching circuit is used. Attach the included 1/4 inch spade connectors to the wire ends and slide them onto the spade plugs inside the unit. When pressure rises above the trip point, COM (pole 3) closes to NO (pole 2); when pressure falls below, COM closes to NC (pole 1). Wire COM-NO for prove-flow logic, COM-NC for prove-no-flow logic.
Which port is high and which is low?
P1 (+) is the high-pressure port; P2 (-) is the low-pressure port. For overpressure monitoring: connect to P1; leave P2 open to atmosphere. For vacuum monitoring: connect to P2; leave P1 open. For differential measurement: higher pressure to P1, lower to P2. For an air filter: upstream (cleaner side) to P1, downstream (loaded side) to P2 - the switch trips when the filter loads up and drives the differential past your trip point.
What accessories do I need?
Recommended: BAPI's BA/APSW-ACC accessory kit - includes 2 total pressure tubes and 2 meters of pressure tubing, the BAPI-engineered pickup for BA/APSW in-duct installations. Alternative pressure pickups from BAPI: ZPS-ACC01 (static pressure pickup port, wall-mounted), ZPS-ACC07 (static pressure probe, in-duct), or ZPS-ACC11 / ZPS-ACC12 (pitot tube assemblies, for airflow proving). Cable should be 0.25-0.375 inch (6.5-9.5 mm) OD to fit the M20 conduit. A digital manometer is helpful for set-point verification during commissioning.
What's the cycle life?
Over 1,000,000 switching operations - among the highest cycle ratings in the industry for HVAC pressure switches. Well-suited for applications with frequent cycling: filter-load alarms that trip and clear daily, intermittent fan-status verification, demand-controlled ventilation interlocks, and any process where the switch sees high duty-cycle action.
What media can this switch handle?
Air and non-combustible, non-aggressive gases: clean ambient air, nitrogen, argon, dry CO2, dry instrument air. The silicone diaphragm is NOT compatible with liquids of any kind, refrigerants, corrosive gases (chlorine, ammonia, hydrogen sulfide, acid fumes), combustible mixtures, or media that will degrade silicone. Burst pressure is 40 inWC (10 kPa) on every range; exceeding this can damage the diaphragm and cause permanent drift or failure.
BA/SW vs BA/APSW - which should I choose?
BA/SW: rectangular hinged-cover enclosure, 6 selectable range springs included in every unit for field range changes, 5A at 125 VAC contact rating, 1/4 inch quick-disconnect terminals, indoor-only (not IP-rated). BA/APSW (this product family): round body with dial adjustment, IP54 or IP65 sealed (outdoor capable), higher-current rating (1.5A at 250 VAC, 3A at 125 VAC, DC ratings), specified accuracy class (+/-1% to +/-5%), 1M cycle life, and BAPI's optional total-tube accessory kit. Choose BA/SW for distributor stocking flexibility and field range swaps; choose BA/APSW for outdoor-rated, higher-precision, or higher-current applications.
What's the warranty?
5-Year BAPI Limited Warranty - covers manufacturing defects in materials and workmanship under normal use. Manufactured in Gays Mills, Wisconsin, USA by Building Automation Products, Inc. ZOT Supply is an authorized BAPI distributor; warranty claims are processed directly with BAPI.
- Series:
- BA/APSW
- Pressure Range:
- 4-20 inWC
- Range Class:
- High
- Contact Style:
- SPDT Form C
- Reset Style:
- Automatic
- Sample Line Fitting:
- 0.24 in (6 mm) plastic pipe
- Maximum Pressure:
- 40 inWC (10 kPa) burst
- Approvals:
- CE, RoHS
- Mounting:
- Vertical (IP65 enclosure)
- Made in USA:
- Yes