Keller Series 21Y
KELLER piezoresistive pressure transmitter with no internal seal, for harsh industrial media.
The 21Y series comprises KELLER piezoresistive pressure transmitters built without an internal seal on the measuring element, which makes them resistant to harsh media and thermal shock. The measuring range covers 0...2.5 to 0...1000 bar, with current output (4...20 mA) or voltage output (0...10 V or 0.5...4.5 V). The full code of a transmitter, for example PAA-21Y 81555.11, shows the type prefix (PA for gauge pressure, PAA for absolute pressure), the 21Y series and the order number of the exact range, signal and connection configuration.
We supply 21Y series transmitters to order from the European Union, in 1–4 weeks, with no stock held in our own warehouse and no publicly displayed price. For a correct quotation, the customer sends the full code from the label of the existing transmitter, for example PA-21Y / 50BAR / 81555.11, the pressure range required and the type of electrical connection wanted. We confirm compatibility in the manufacturer's current documentation before sending the quotation.
Models and codes
| Code | Note |
|---|---|
| PAA-21Y 81555.11 | order code supplied by the customer, absolute pressure configuration |
| PA-21Y / 50BAR / 81555.11 | gauge pressure variant, 0–50 bar, 4–20 mA output |
| PA-21Y / 25BAR / 81554.33 | 0–25 bar, 4–20 mA output, G1/4 thread |
| PAA-21Y / 2.5BAR / 81554.33 | absolute pressure, 0–2.5 bar, 0–5 V output |
| PA-21Y / 100BAR / 81684.33 | 0–100 bar, M12 connector |
Key specifications
| Pressure range | 0...2,5 – 0...1000 bar |
|---|---|
| Accuracy | ≤ ±0.5 %FS |
| Total error band | ±1.5 %FS at -10...80°C |
| Output signal | 4...20 mA / 0...10 V / 0.5...4,5 V |
| Supply voltage | 8...32 VDC |
| Measured medium temperature | -20...125 °C |
| Insulation voltage | 300 VDC |
The manufacturer's datasheet for the 21Y series is dated March 2025, and the product documentation is active, with no withdrawal notice.
Frequently asked questions
What do I need to send for a quotation on the 21Y series?
The full code from the label of the existing transmitter, for example PA-21Y / 50BAR / 81555.11, plus the pressure range and the type of electrical connection used in the installation. If the label is no longer legible, the pressure range and the signal type (current or voltage) are enough.
What do we check before quoting for the 21Y series?
We do not confirm from our own sources the exact IP protection class for each electrical connection variant; it depends on the connector chosen and is checked case by case in the current datasheet before quoting.
Other Keller series
The range of electrical connectors available for each pressure range is established by code, on request.
Updated: 2026-11-12