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About this part

The 1pc Keyence Pressure Switch AP-51A New is made by KEYENCE and identified by manufacturer part number AP-51A.

This listing is for the exact part number stated above. Compare the part number, condition and photos with your equipment before ordering.

Condition

This item is listed as New – Open Box. Unused. Packaging opened or missing.

The photos are part of the description — check them for labels, connectors, markings and any visible wear.

What's included

1 × 1pc Keyence Pressure Switch AP-51A New.

Only the items listed here or clearly shown in the photos are included. Cables, manuals, mounting hardware and accessories are not included unless stated.

Identification & compatibility

Check the manufacturer (KEYENCE), the part number (AP-51A) and the photos against your equipment. If you are not sure this is the right part, contact us before you order.

Price match

Found an identical item for less at a fixed price elsewhere? Contact us before you buy with the details, and we will review it.

Important information

Product information is based on what is available for this specific item. Where specifications or compatibility are critical to your application, confirm them before purchase.

Brand
KEYENCE
Part number
AP-51A
Model
AP-51A
Country of Origin
Japan
Series
Keyence AP-50 compact pressure sensor
Type
Negative pressure, NPN, analog type
Rated pressure
0 to −101.3 kPa (gauge)
Compatible media
Gases and liquids compatible with SUS630 and SUS304
Display
4-digit, 7-segment LED, 8 mm character height, 0.1 kPa resolution
Control outputs
NPN open collector, 100 mA max. (40 V or less), residual voltage 1 V or less, N.O./N.C. switchable; OUT1 and OUT2 per unit label
Analog output
4 to 20 mA, max. load resistance 300 Ω
Response time
5 ms
Repeatability
±0.5% of F.S. ±1 digit or less
Power supply
12 to 24 VDC ±10%, ripple (p-p) 10% or less
Current consumption
75 mA or less
Pressure resistance
500 kPa
Enclosure rating
IP67
Ambient temperature
−10 to +50 °C
Material
Wetted parts SUS630 and SUS304; case PBT and die-cast zinc
Weight
Approx. 185 g

The Keyence AP-51A is a compact negative-pressure (vacuum) sensor from Keyence's AP-50 series, with NPN switching outputs and a 4–20 mA analog output. It measures gauge pressure from 0 to −101.3 kPa, shows the reading on a 4-digit LED display, and runs on 12 to 24 VDC. Each unit is sold individually (1 pc). The AP-51A is also searched as AP51A. Full ratings are in the Specifications tab.

What is the difference between the AP-51 and the AP-51A?

Both are Keyence negative-pressure NPN sensors with the same 0 to −101.3 kPa range. The AP-51A adds a 4–20 mA analog output (maximum load 300 Ω), which appears as the pink ANALOG OUT wire on the unit's rear label. Note that the negative-pressure type displays vacuum as a positive number: −50.0 kPa is shown as 50.0 kPa.

How is the AP-51A wired?

The rear label gives the colour code: brown 12–24 V DC, blue 0 V, black OUT1, white OUT2 and pink analog output. The switching outputs are NPN open collector, 100 mA max. at 40 V or less, and can be set to N.O. or N.C. Response time is 5 ms.

What condition are these sensors in?

New, open box. The photos show the sensors in their plastic bags, each with its pre-wired cable and a metal mounting bracket attached. A white sticker covers part of the front panel of the unit in the main photo.

Ships from
Israel
Tracking
Included on every order

Import duties and taxes may apply in your country and are paid by the buyer on delivery.

Returns
Not accepted

Return terms differ from item to item — this item's own policy is shown above.

Whatever it says, an item that arrives faulty or not as described is covered: tell us within 30 days of delivery and we will refund or replace it.

Consumers in the EU, the UK and Israel keep their legal right to cancel within 14 days. Full details and the return request form are on our Returns and warranty page.

Read the full returns & warranty policy

Questions about this part

What pressure range does the Keyence AP-51A measure?

0 to −101.3 kPa gauge pressure (vacuum). The display shows vacuum as a positive value, so −50.0 kPa reads as 50.0 kPa.

Does the AP-51A have an analog output?

Yes. It has a 4–20 mA analog output with a maximum load of 300 Ω, on the pink wire, in addition to its NPN switching outputs.

What are the wire colours of the AP-51A?

Brown 12–24 V DC, blue 0 V, black OUT1, white OUT2 and pink analog output, as printed on the rear label.

Is the AP-51A NPN or PNP?

NPN open-collector outputs, 100 mA max. at 40 V or less, switchable between N.O. and N.C.

How many sensors do I get?

One sensor per purchase.

Over 1,000 positive reviews from our customers

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