Heat And Cold Retention Procedures; Type U - Oval ALTI mass CA00A Instructions Manual

L -- 740 -- 28 -- E

6.7 Heat and Cold Retention Procedures

When the fluid to be measured requires temperature retention at low or high temperature, you can keep
the sensor unit at high or low temperature. Here, correct heat retaining and cold retaining methods are
described.
(1) When installing heat retaining or cold retaining material on the sensor unit, apply heat retention or
cold retention to only main body. As the fluid passes through the sensor case, heat retention or
cold retention on the mounting tube and terminal box has no effect. Especially, in the case of high
temperature type and low temperature explosionproof type, do not install heat retaining or cold
retaining material within a distance of 20mm from the mounting tube so that the terminal box is
protected against heat (heat and cold) (see Fig. 6.22).
(2) For easy maintenance, a simplified heat retaining system is recommended on the sensor unit.
(3) When covering the heat insulating material with outer sheath for heat retention or cold retention,
if the natural frequency of the outer sheath is close to the frequency of the tube oscillating in the
sensor unit *1, it may possibly cause some effect on the measurement.
(4) Careful attention should be paid to the maximum permissible temperature when steam trace is
applied. Trace temperature should be the same as that of the metered fluid. (⇒ See 3.1 Sensor
Unit General Specifications).
(5) If you plan to spirally wind copper tubing or similar around the sensor unit, secure the copper tubing
with pipe retainers shown in Figs. 6.21 through 6.25 - and spot weld the copper tubing to the sensor
unit.
(6) Use of heat tracer is recommended for CA025, CA040, CA050, and CA080 of TypeU.
*1：The frequency band for CA100 to CA250 will be 70 to 100Hz.
NOTE: Vibrating copper tubing caused by the flowmeter in operation can produce zero shifts. In such
a case, increasing the number of fixed points is one solution that will work.
NOTE: To minimize transmission of oscillation to the sensor, the spirally wound copper tubing should
start and end at the manifold of flanged sensor housing.
NOTE: Sudden temperature change may damage the performance of the flowmeter. Keep the
temperature change of the fluid within ±12℃ /min. for both heating and cooling.
CAUTION: 1. Do not use electric heaters which could be a source of noises.
2. If ambient temperature around the transmitter is expected to exceed 55° C,
separately mounted type is recommended.

6.7.1 Type U

CA00A, CA001 and CA003
●
Terminal box
Copper tubing
Sensor unit
〔CA00A, CA001〕
0
Piping
Spot weld
Steam
Pipe retainer (material SUS strip)
Fig.6.21
Copper tubing
〔CA003〕