User manual VAISALA HMP140A

[. . . ] 4 3. 2. 2 Mounting the HMP142A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. 2. 3 Mounting the HMP143A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Electrical connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Connectors and potentiometers on the main PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] For example, at +20 C (+ 68 F) and 50 %RH, a temperature difference of +1 C between the measured object and the sensor causes an error of +3 %RH. The error is at its greatest when the temperature of the sensor differs from that of the surroundings and the humidity is high. A few degrees' difference in temperature may cause water to condense on sensor surface. Efficient ventilation accelerates evaporation whereas in an unventilated space, it may take hours. The HUMICAP180 sensor returns to its normal functioning as soon as water has evaporated. Any contaminated water condensing on the sensor may shorten its life span and change the calibration. 10 9 8 7 dRH (%RH) 6 5 4 3 2 1 0 -40 -20 0 20 40 60 80 100 Temperature (C) Figure 2. 1 Measurement error at 100 %RH when the temperature difference between the ambient and the sensor is 1 C 2 1999-12-08 U175en-1. 5 HMP140A SERIES Operating Manual 3. 3. 1 INSTALLATION Selecting the place of installation Select a place that gives a true picture of the environment or process and is as clean as possible. A rapid air flow is recommended as it ensures the same temperature for the ambient air and the sensor head. Install the transmitter in a place where no cold or hot spot can develop. If the sensor head is installed in a duct or channel where the temperature is different from the ambient temperature, insulate the point of entry; this is particularly important if the transmitter is installed with the sensor head pointing downwards. Vertical installation of the HMP142A and HMP143A is not recommended; they should be mounted with the sensor head horizontally whenever possible. An uninsulated installation might lead to condensation on the sensor head and even if no condensation occurs, the resultant air flow may change the temperature near the sensor head and distort the readings. 3. 2 Mounting The electronics of the HMP140A series can be disconnected for ease of installation and service. The housing can be conveniently installed and the electronics then consequently mounted. For service and maintenance purposes the electronics can be disconnected without disconnecting the cabling, and taken to an appropriate environment for necessary adjustments. 60 6. 5 83. 5 60 4. 2 Figure 3 1999-12-08 Drilling dimensions (in mm) 3 HMP140A SERIES Operating Manual U175en-1. 5 3. 2. 1 Mounting the HMP141A The optimal installation of the HMP141A is with the sensor head pointing downwards. Mounting and wiring: cable feedthrough on the surface or in the connection box. Push the sensor head through the protection lid as in figure and connect the electronics housing to the connection box. Make sure that the pins at the bottom of the electronics housing are in contact with the screw terminal. Close the cover and fasten the two connection screws. 4 1 6 4 4 4 5 2 3 Figure 3. 2. 1 3. 2. 2 Mounting of the HMP141A Mounting the HMP142A The HMP142A transmitter should be mounted with the sensor head horizontally whenever possible. This way, any water that might condense on the tube cannot flow on to the sensors. When there is no alternative but to install the sensor head in the process vertically, the point of entry must be carefully insulated. 4 1999-12-08 U175en-1. 5 HMP140A SERIES Operating Manual 225 15 12 Figure 3. 2. 2 3. 2. 3 Dimensions of the HMP142A (in mm) Mounting the HMP143A The cable model HMP143A should also be mounted with the sensor head horizontally whenever possible. Mount the nuts on the sensor head: disconnect the cable from the transmitter, insert the nuts and fasten them on the sensor head. The cable can also be extended up to 100 metres; see Appendix 3 for details. duct wall a plugged hole for reference measurements flange sealing M12x1 12 supporting bar 69 Figure 3. 2. 3 Dimensions of the HMP143A probe (in mm) and installation in a channel with the help of flange (part no. HMP233FA) and supporting bar 1999-12-08 5 HMP140A SERIES Operating Manual U175en-1. 5 3. 3 Electrical connections The wiring can be done in either of the two ways shown in Figure 3. 3. [. . . ] A shielded cable is recommended as it ensures the best possible EMC protection. The diameter of the cable should not exceed 7 mm as larger cables do not fit to the lead-through of the transmitter. The HMP143A probe head uses a combined signal ground and supply voltage ground. Ground wire resistance Rc causes an offset type error to the transmitter output. [. . . ]