Siemens ET 77E Series Especificaciones descargar pdf (Pagina 26)

SD77

2.3 PIPING

The supply (IN) and output (OUT) connections on the transducer are 1/4 inch NPT. See Figure 2-1. Quarter-inch

O.D. tubing is recommended for piping to the transducer. Before making connections, blow out all piping.

Use pipe sealant sparingly and then only on the male threads of the tube fittings. A non-hardening sealant is

strongly recommended.

There must be no leaks, especially in the output. Leak test all fittings and tube connections.

2.4 TRANSMISSION DISTANCE

If the installation requires the transducer to transmit its output pressure for distances greater than 50 feet (15

meters), a Siemens (or Moore Products Co.) Model 61F 1:1 Booster Relay may be required. Use of the booster relay

depends upon the frequency response requirements of the system. If a booster relay is used, connect it to the

transducer output with a minimum of 2 to 3 feet (0.6 to 1 meter) of 1/4" O.D. tubing.

2.5 TAPPED EXHAUST

A transducer with the tapped exhaust option provides the capability to pipe its exhaust flow away from the vicinity

of the transducer. This is an important option when a gas other than air is used for the supply. Figure 2-5 locates the

tapped exhaust port.

As shipped from the factory, sealing screws are installed in the condensation

drain hole and the two normal exhaust ports.

IMPORTANT

Do not use the condensation drain feature with the

tapped exhaust option. The drain hole is a

discharge path for the transducer's

exhaust.

FIGURE 2-5 Tapped Exhaust Port

2.6 EXHAUST PORT SELECTION

The transducer has two exhaust ports: one at the front of the top housing (Figure 2-1) and the other above the

terminal block in the terminal enclosure (Figure 2-6). As shipped, two sealing screws are installed: one is installed

in the external exhaust port at the front of the top housing, and a second is installed in the condensation drain. This

configuration allows the transducer's exhaust air to purge the terminal enclosure, the conduit, and associated

electronic enclosure (if used).

CAUTION

Do not remove either the exhaust sealing screw or the condensation drain sealing screw

in a Class II hazardous location or where a 4 or 4X Enclosure Type is required.

If airtight conduit, conduit fittings, and electronic enclosures are used, move the exhaust sealing screw to the

internal exhaust port in the terminal enclosure (Figure 2-6) and remove the condensation drain sealing screw. This

allows the transducer exhaust to be vented to atmosphere through the external exhaust port. It also allows any

accumulated condensation from the instrument air supply to drain from the coil cavity.

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Siemens ET 77E Series Especificaciones Pagina 26