Yokogawa EJX118A - Manual (Page 23)

<4. Installation>
4-1
IM 01C25H01-01E
4. Installation
4.1 Precautions
Before installing the transmitter, read the cautionary
notes in Section 2.4, “Selecting the Installation
Location.” For additional information on the ambient
conditions allowed at the installation location, refer
to Subsection 8.1 “Standard Specifications.”
IMPORTANT
• When welding piping during construction,
take care not to allow welding currents to
flow through the transmitter.
• Do not step on this instrument after
installation.
• For the EJ438, there is a small hole in
the low pressure side cover flange that is
used to measure the atmospheric pressure.
The hole must not face upward. See section
8.4, “Dimensions,” for the location of the
hole.
• Never loosen the four bolts securing the
cover flanges (Refer to figure 3.2.) If the seal
liquid leaks, the transmitter cannot be used.
4.2 Mounting the Diaphragm
Seals
Mount the diaphragm seals using the flanges as
shown in Figure 4.1 Figure 4.2 shows how to mount
the diaphragm seals on a tank. The mating flange,
gasket, bolts and nuts are to be procured by the
customer.
Nut
Flange
Diaphragm
Ød
Gasket
F0401.ai
Bolt
The product is shipped with
these parts assembled.
Correctly install the diaphragm seals on
the high and low pressure sides of the
process (The label on each diaphragm
seal is marked HIGH or LOW.)
Figure 4.1 Mounting the Diaphragm Seals
IMPORTANT
Please use a gasket with an inside diameter
(ød) that is greater than the diameter of the
diaphragm seal. If a gasket with a smaller
inside diameter is used, the diaphragm may
not function correctly. (Refer to Subsection 8.4
‘Dimensions’)
IMPORTANT
• When measuring the liquid level of the tank,
the minimum liquid level (zero point) must
be set to a level at least 50 mm above the
center of the high pressure side diaphragm
seal (see Figure 4.2).
• Correctly install the diaphragm seals on the
high and low pressure sides of the process,
checking the label on each seal.
• To avoid measuring error duets temperature
difference between the two diaphragm
seals, capillary tube must be bound together.
The capillary tube must be securely fixed
to the tank wall to prevent movement by
wind or vibration. If the capillary tube is too
long, loosely coil the extra tube portion (coil
diameter of 300 mm or more) and secure the
coiled tube with a clamp.
• During the diaphragm seal installation,
ensure as far as possible that no seal liquid
head pressure is applied to the diaphragm
seals.
• Exercise care so as not to damage
diaphragm surfaces. Since the diaphragm
protrudes approx. 1 mm from the flange
surface, do not place the pressure detector
section face down on a surface as this can
damage the diaphragm.
• Do not sharply bend or twist capillary tube or
apply excessive stress to them.