SOP - TEMPERATURE AND RELATIVE HUMIDITY MONITORING

1.0
PURPOSE:
To provide a written procedure for usage and maintenance of wet and dry bulb Hygrometer & to
provide a schedule and acceptance criteria for Temperature & Relative humidity (RH) recorded
in controlled areas.
2.0
SCOPE:
Applicable to all wet and dry bulb hygrometers used for checking temperature and relative humidity in controlled areas within Factory premises.
3.0
RESPONSIBILITY:
Concerned Departmental Executives and Departmental Heads.
4.0
ACCOUNTABILITY:
Plant Manager and Manager Quality Assurance
5.0
DEFINITIONS:
Nil.
6.0
PROCEDURE:
6.1
PREPARATION OF THE INSTRUMENT:
6.1.1
Check and ensure that the wick is fixed on the wet bulb hygrometer.
6.1.2
Fill the cistern with potable water at the start of the shift.
6.1.3
Check and ensure that the wick is wet.
6.1.4
Check the mercury columns of the thermometer for any break in the column before taking to the area to be monitored
6.2
OPERATION:
6.2.1
Remove the hygrometer from the pouch and rotate gently for 50 to 60 times moving around the whole cubicle to cover the entire manufacturing area in the cubicle and then note the reading of wet and dry bulb hygrometer.
6.2.2
Subtract the reading of the wet bulb from that of dry bulb column, thus arriving at the depression value.
6.2.3
Refer Temperature and Humidity Chart to locate the readings of dry bulb and the depression value given by the hygrometer. Read the % RH at the intersection of the two columns. In case values of dry bulb and depression of wet bulb fall between those indicated on chart, interpolate the values as given below.
6.2.4
The dry bulb reading indicates the temperature of the area.
The following examples illustrate the method of using the table.
6.2.4.1
Dry Bulb temperature …. …. …. 30ºC
Wet Bulb temperature …. …. …. 25ºC
Hence the depression of the Wet Bulb : 30ºC - 25ºC = 5ºC
Reading directly from the tables, the relative humidity is 65 %.
6.2.4.2
Dry Bulb temperature …………. 23.5ºC
Wet Bulb temperature ………….16ºC
The depression of the wet Bulb: 23.5ºC – 16.0ºC =7.5ºC.
In order to find the relative humidity, it is necessary to interpolate between the “Dry Bulb” columns 23 and 24 and the “Depression of Wet Bulb” columns 7.5.
The readings are as follows:
Dry Bulb 23ºC.
Depression of Wet Bulb 7.5ºC
RH % reading 41%
Dry Bulb 24ºC
Depression of Wet Bulb 7.5ºC
RH % reading 43%
The mean of two readings i.e. 41 & 43 is 42.
Hence the relative humidity is 42%.
6.2.5
Record the Temperature & Relative Humidity at about 10.00 hrs +30 mins,
14.00 hrs +30 mins, and 16.30 hrs + 30 min. Refer the format ‘Temperature and Relative Humidity Record’ QAGN: 003:F1.
6.2.6
The area and operating range for temperature and relative humidity is mentioned in Annexure XXXXXXX
6.2.7
If any discrepancy is observed, Inform to Q. A. & Maintenance Dept. and further action should be taken in consultation with Unit head through enclosure QAGN:003:F2
6.3
MAINTENANCE:
6.3.1
Ensure that sufficient potable water is available in the cistern.
6.3.2
Ensure that the wick is wet and the bottom end is always immersed in filtered potable water.
`6.3.3
Ensure that the top end of the wick covers the bulb completely. (To ensure this, the wick may be fastened or tied to the wet bulb).
6.3.4
Check and ensure that no scales or deposit are observed on the wick. Replace the wick as and when required.
6.3.5
Change the filtered potable water in the cistern daily or as and when required.
6.3.6
Hygrometer should be calibrated after every six months by approved external agency.
6.4
PRECAUTIONS TO BE TAKEN DURING HANDLING OF HYGROMETER
6.4.1
Ensure that product in the respective area is in closed condition.
6.4.2
Before swinging the hygrometer in the air, ensure that the hygrometer will not hit with the wall or with the near by equipment.
6.4.3
While handling it, if hygrometer is damaged inform to QA and get replaced with new calibrated hygrometer.
7.0
REFERENCES:
Nil
8.0
ENCLOSURES:
8.1
Temperature & Relative Humidity Record : XXXXXXX
8.2
Intimation Note to QA and Maintenance Dept
for Temperature and Relative Humidity Corrections : XXXXXXX
8.3
Area & Acceptance Criteria : XXXXXXXX
9.0
ABBREVATIONS :
9.1 °C : Degree Centigrade
9.2 % : Percentage
9.3 RH : Relative Humidity
9.4 Q. A. : Quality Assurance