IM100CZ04-E4
3
If the pressure sensor is used for screen changer operation, it may
suffer an impact during screen changer operation, causing sensor
troubles. In such a case, carefully consider the position and
direction when installing the sensor.
Mounting pressure sensors
When the diaphragm at the end of CZ-100P and its surroundings
completely touch with its mounting hole, large indication error may
occur. In this case, temperature may exert a large influence
especially upon the zero point. Therefore, much attention should
be paid when a mounting hole is drilled.
When using a lead pipe cover, pay attention that the lead pipe
cover end does not directly touch the barrel. (Refer to the “
Exposed length at the bottom of the sensor outer case
”)
Prior to mounting the pressure sensor, check the appearance of
the diaphragm. If the diaphragm has a deformed or abnormal end,
it needs to be repaired or re-calibrated. As there is a case where
the diaphragm is already deformed by the application of overload
when used previously, carefully check its condition before the
pressure sensor is re-used.
Mounting hole
When mounting the pressure sensor, check its mounting hole
dimensions. (Do not overtighten its screw.
)
If resin or its carbide still remains in the mounting hole, this may
damage the pressure sensor. Therefore, prior to mounting the
sensor, always remove any residue from the mounting hole.
Check that the diaphragm surface does not protrude from the
inner wall of the barrel, since this may score the diaphragm
surface with the screw, etc. If necessary, adjust the position
between the diaphragm surface and the inner wall of the barrel
using stainless steel gaskets, etc.
For the loose nut type, resin leakage may occur more easily than
the fixed nut type, as the pressure sealing surface becomes wider.
If any resin leaks through the mounting gap of the sensor, use
copper gaskets (thickness: t
2 mm) or aluminum gaskets
(thickness: t
2 mm) by taking into account the position between
the diaphragm surface and the inner wall of the barrel. (Copper
Gasket: Included in only the Loose nut type)
Mounting direction
If the sensor is installed in the upright direction (Fig.1-A), it may be
affected directly by heat flow from heater or heat source (rising
current of heated air). In such a case, the temperature of the strain
gauge in the sensor may exceed an allowable maximum
temperature of 150
C. In order not to exceed this limit
temperature, it is necessary to keep the sensor outer cylinder
surface at a temperature of less than 134
C (Fig.2). Conduct the
following treatments.
1.
In order to avoid heat flow, wind a heat insulating material round
such a heat source (heater, etc.).
2.
Further extend the length of the exposed lead pipe.
In order to keep the specified sensor performance longer, it is
recommended that the sensor outer cylinder surface temperature
be keep at less than 134
C.
When the sensor is installed in the upright position, thermal effects
on the sensor may not sufficiently lessen even if the length of the
exposed lead pipe is further extended. In this case, take measures
of
1
.
The effect of heat flow lessens as the installing direction of the
sensor changes from the slanting direction (Fig.1-B) to the
horizontal direction (Fig.1-C) in this order. In this case, take
measures of
1
and
2
if necessary by checking the sensor outer
cylinder surface temperature. (To the relevant manufacturer: It is
recommended that the sensor be installed in the horizontal or
slanting direction in order to lessen the effect of heat on the strain
gauge.)
Exposed length at the bottom of the sensor
outer case
Cases where the temperature of the strain gauge in the sensor
become less than 150
C is as follows:
The effect of heat flow is small.
The sensor is installed in the upright position.
The diaphragm is at a temperature of 400
C.
The length of the exposed sensor outer cylinder is more than
70 mm. (Refer to below)
However, as the effect of heat flow from an actual extruder is
serious, if there is no enough exposed section below the sensor
outer cylinder even at a diaphragm temperature of less than
200
C, the operating temperature of the sensor strain gauge may
exceed its limit. Therefore, check the temperature environment
where the sensor is installed (by indirectly checking the
temperature of the sensor outer cylinder surface), and take
necessary measures to lessen the temperature of the sensor
strain gauge by using a heat insulating material, if necessary.
If the temperature of the sensor outer cylinder surface
exceeds 160
C, the outer cylinder surface changes its
color from black to dark brown and then brown in this
order. If it exceeds 180
C, the color may change to silver.
A lead pipe cover is mainly for protecting the exposed section below
the sensor outer cylinder from being exposed to cold wind.
Therefore, do not install the sensor such that it is embedded in the
heat source (such as in the barrel or heater) together with the lead
pipe cover. This may heighten thermal conductivity from the heat
source, resulting in a temperature increase in the sensor strain
gauge.
3.1.2 Caution in removing pressure sensors
Always remove the sensor while resin is being melted
, since
the diaphragm of the sensor may be damaged if the sensor is
removed after the resin has hardened. If the sensor is re-mounted
under this condition the repeatability may deteriorate.
When removing the pressure sensor, remove it under the same
temperature as that during installation. Removing the pressure
sensor under the different temperature as that during installation
cause irregular engagement of the thread.
If resin flows into the gap between the lead pipe and the mounting
hole, it may be impossible to remove the sensor even with the
threads completely disengaged. In this case, if the sensor is
forcibly removed using a puller, the sensor may be knocked when
removed, damaging the diaphragm and reducing the accuracy.
Slowly remove the sensor without knocking it.
Do not wind sealing tapes, etc. round this section
for preventing oil or resin leakage.
Packing surface (Sealing surface)
[Flat tightening or tapered tightening surface]
(Oil or resin leakage is prevented at this point.)
Barrel
Lead pipe cover
Mount the sensor so that this block
does not directly touch the barrel.
The aims of a
temperature
measurement
position
(Fig. 2)
(Fig. 1)
A: Upper mounting
B: Oblique mounting
C: Side mounting
A section of a extruder
A
B
C
Mounting environment:
Ambient temperatures
at room temperatures
25
C
CZ-100P
Mounting adapter
Temperature of heater
400
C
90
60
70
(Unit: mm)
