Page 6 of catalogue Non-Contact Pneumatic Sensors of Festo AG & Co. KG

Non-Contact Pneumatic Sensors
Back Pressure sensors Back Pressure End Stop Type SD-2 Type SD-3
Type Y-PK-3-D Type SD-2

Barbed Restrictor Y-Connector Type Y-PK-3-D Mounting Block for SD-3 Type SDA-12 x 1-B
Back pressure sensors are used as Limit switches and end stops to transmit signals dependent upon distance. Type SD-3 can be used as an air barrier sensor in combination with the SML-40-S ejecting nozzle. See page 200. These devices are especially suited for limit sensing and positioning control where a high degree of accuracy is required and where available operating forces are minimal. Because of their small size, they can be used in inaccessible areas at varying ambient temperatures and in a dirty atmosphere. The mounting block, Type SDA-12 x 1-B, securely holds the SD-3 when it is used as a limit stop (end stop).
Type SD-2 Type SD-3

Type SD-3

The back pressure sensor is connected to the compressed air supply at connection P (black). With the valve in open position, the air flows outward. If the nozzle is blocked, a signal appears at outlet A (yellow), which may reach as high as the supply pressure. The signal will remain as long as the nozzle is blocked. The back pressure sensor, Type SD-2, is used with a separate air supply throttling system. The restrictor Y-fitting, Type Y-PK-3-D, may be used for this purpose (connection P with 0.016 in / 0.4 mm throttle black, connection A yellow). The following measures are recommended to reduce air consumption: (a) Supply the back pressure nozzle with compressed air only if a signal is to be generated. (b) Install a needle valve in air line P if the pressure is greater than 45 psi / 3 bar. If the signal pressure from the sensor does not equal the actuating pressure required for the downstream unit, a pressure amplifier must be used.

P = Supply A = Outlet

Order Number Medium Mounting Mounting Hole Diameter Connection Orifice Size Supply Pressure Range at P* Signal Pressure Range at A Air Consumption Min. Closing Force Ambient Temperature Design Material Weight

Part No./Type

7455 SD-2 4498 SD-3 7456 Y-PK-3-D Compressed air (filtered, lubricated or unlubricated) M6 M12 x 1 with Tubing connections with mounting Nuts mounting nuts 0.26 in / 6.5 mm 0.5 in / 12.5 mm Barbed fitting for 3/16 in / 3 mm tubing 0.098 in / 2.5 mm (throttle 0.016 in / 0.4 mm) 0 to 120 psi / 0 to 8 bar See graphs on page 226 See graphs on page 227
8.9 psi / 0.615 bar x 12 psi / 0.83 bar x supply pressure supply pressure

11541 SDA-12 x 1-B Through holes

-40 to +212°F / -40 to +100°C† Nozzle, no moving parts Stainless steel (face-hardened), brass. Seals: Buna N. 0.015 lb / 0.007 kg 0.044 lb / 0.020 kg

14 to 140°F / -10 to +60°C

Brass, plastic 0.011 lb / 0.005 kg

Steel, galvanized 0.265 lb / 0.120 kg

*14 to 140°F / -10 to +60°C

† Depending on tubing used.
(Ref. 8.4/20-1, 10.3/10-1) (98)

188

Subject to change