Siemens ET 77E Series Especificaciones descargar pdf (Pagina 31)

SD77

5.0 MAINTENANCE

This section presents transducer maintenance procedures.

CAUTION

Improper servicing and/or substitution of components may impair the electrical safety

of this instrument.

5.1 PREVENTIVE

As with most pneumatic instruments, a clean, dry and oil-free supply air is recommended. Refer to the Instrument

Society of America’s “Quality Standard for Instrument Air” (ISA-S7.3).

5.2 CLEANING

The transducer filter screens, restriction screw, nozzle and nozzle seat can be cleaned without dismounting the

transducer.

When the transducer top housing is removed, take care to prevent metal chips, dirt, and other contaminants from

entering the coil chamber. These foreign objects can interfere with coil movement and may change the magnetic

field.

5.2.1 Filter Screens

There is a filter screen in the supply (IN) port and in the output (OUT) port.

1. Disconnect the tubing and remove the tube fittings.

2. Remove the four screws from the top housing and remove it by pulling straight up.

3. Blow the screens down in a reverse direction. Remove the restriction screw, cover the nozzle opening, and

blow air into the port from which the restriction screw was removed. If the dirt is not dislodged, loosen it

mechanically or chemically and repeat the blow down procedure.

4. If a screen is damaged or cannot be cleaned it must be replaced. Each screen is retained by a fiber washer. Be

sure replacement fiber washers are on-hand before removing a screen. When installing a screen, it should be

firmly retained at the bottom of its port by a fiber washer.

5.2.2 Restriction Screw

Remove the restriction screw (stamped R) from the top-center of the transducer. The restriction is accessible from

the tip of the screw. Cleaning with a solvent is usually sufficient. If necessary, run a 0.021-inch drill blank through

the restriction until it can be seen in the cross-drilled hole.

5.2.3 Nozzle and Nozzle Seat

The nozzle is part of the top housing. The nozzle seat is in the transducer housing; the seat is the top end of the

center shaft.

1. Disconnect the tubing and remove the four screws from the top housing.

2. Remove the top housing by pulling it straight up.

3. Clean the nozzle and nozzle seat by wiping with a dry cloth or a solvent dampened cloth. Do not use abrasive

cleaning agents. The important parts of the nozzle to clean are its inner diameter surfaces and the sharp edge of

its face.

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Siemens ET 77E Series Especificaciones Pagina 31