YOKOGAWA Dpharp EJA438N User Manual Download Page 10

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IM 1C22J1-01E

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2. HANDLING CAUTIONS

(b) Ambient Atmosphere

Avoid installing the transmitter in a corrosive
atmosphere. If the transmitter must be installed in a
corrosive atmosphere, there must be adequate
ventilation as well as measures to prevent intrusion
or stagnation of rain water in conduits.

Select an installation site suffering minimum shock
and vibration (although the transmitter is designed
to be relatively resistant to shock and vibration).

(d) Installation of Explosion-protected Transmitters

Explosion-protected transmitters can be installed in
hazardous areas according to the types of gases for
which they are certified. See Subsection 2.9
“Installation of Explosion Protected Type Transmit-
ters.”

2.5 Pressure Connection

WARNING

• Instrument installed in the process is under

pressure. Never loosen or tighten the flange
bolts to avoid the dangerous spouting of
process fluid.

• Since the accumulated process fluid may be

toxic or otherwise harmful, take appropriate
care to avoid contact with the skin, eyes or
body, or inhalation of vapors even after dis-
mounting the instrument from process line for
maintenance.

The following precautions must be observed in order to
safely operate the transmitter under pressure.

(a) Never apply a pressure higher than the specified

maximum working pressure.

(b) Never loosen or tighten the bolts securing the

diaphragm seal flanges when the assembly is under
pressure. Do it after releasing the process pressure
if required.

2.6 Waterproofing of Cable

Conduit Connections

Apply a non-hardening sealant to the threads to
waterproof the transmitter cable conduit connections.
(See Figure 5.4.2a, 5.4.2b and 5.4.2d.)

2.7 Restrictions on Use of Radio

Transceiver

IMPORTANT

Although the transmitter has been designed to
resist high frequency electrical noise, if a radio
transceiver is used near the transmitter or its
external wiring, the transmitter may be affected
by high frequency noise pickup. To test for such
effects, bring the transceiver in use slowly from a
distance of several meters from the transmitter,
and observe the measurement loop for noise
effects. Thereafter, always use the transceiver
outside the area affected by noise.

2.8 Insulation Resistance and

Dielectric Strength Test

Since the transmitter has undergone insulation resis-
tance and dielectric strength tests at the factory before
shipment, normally these tests are not required.
However, if required, observe the following precau-
tions in the test procedures.

(a) Do not perform such tests more frequently than is

absolutely necessary. Even test voltages that do not
cause visible damage to the insulation may degrade
the insulation and reduce safety margins.

(b) Never apply a voltage exceeding 500 V DC (100 V

DC with an internal lightning protector) for the
insulation resistance test, nor a voltage exceeding
500 V AC (100 V AC with an internal lightning
protector) for the dielectric strength test.

lines from the transmitter terminals. Perform the
tests in the following procedure:

• Insulation Resistance Test

1) Short-circuit the + and – SUPPLY terminals in the

terminal box.

2) Turn OFF the insulation tester. Then connect the

insulation tester plus (+) lead wire to the shorted
SUPPLY terminals and the minus (–) leadwire to
the grounding terminal.

3) Turn ON the insulation tester power and measure

the insulation resistance. The voltage should be
applied short as possible to verify that the insula-
tion resistance is at least 20 M

Ω