Ashcroft 4480 - Pneumatic Transmitter Manual de usuario descargar pdf (Pagina 5)

ir Connections

onnect the LOW pressure instrument air SUPPLY to the

⁄

female NPT connection, marked SUPPLY, at the left of the

process pressure connection. The instrument air is to he

lean, dry, and liquid free. Connect the remote equipment

line to the

⁄

4 female NPT connection, marked OUTPUT, at

the right. The use of metal or plastic tubing in place of piping

s strongly recommended. It is important that the transmitted

airline be free of leaks: the use of metal or plastic tubing

reduces the possibility of leaks. The supply air pressure

equired for 3-15 psi transmitted range is 18-20 psi.

he supply air pressure required for 3-27 psi transmitted

range is 30-35 psi.

Any number of pneumatic receivers may be connected to the

transmitted air line. However, the total length of the transmit-

ted air line should not exceed 1000 feet, or the speed of

response will be reduced. Response speed versus line length

for various sizes of tubing Is shown In Figure 6.

Figure 6. Response Speed versus Tubing Diameter and Length

0 100 200 300 400 500 600 700 800 900 1000

FEET OF TUBING

TIME IN SECONDS

RESPONSE TIME

TIME REQUIRED TO CHANGE

RECEIVER INDICATION 100%

⁄

I.D. TU

BIN

⁄

TUBI

⁄

I.D.

I&M008-10061-1-01 250-1969-C_I&M008-10061-1/01 250-1969-C 12/20/13 9:09 AM Page 5

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Ashcroft 4480 - Pneumatic Transmitter Manual de usuario Pagina 5