Gastec 91P Instructions

Instructions for
Formaldehyde Detector Tube
No.91P
FOR SAFE OPERATION :
Read this manual and the instruction manual of your Gastec Air Sampling Pump carefully.
CAUTION : If not observed, injuries to the operator or damage to the
product may result.
1. When breaking the tube ends, keep away from eyes.
2. Do not touch the broken glass tubes, pieces and reagent with bare hand(s).
NOTES : For maintaining performance and reliability to the test result.
1. Recommend to use Gastec Gas Sampling device Model GSP-300FT-2 (if not available use the air
sampler of equivalent to sample for 200 mL/min) together with Gastec Detector Tubes only for the
purposes specified in the instruction manual of the detector tube.
2. Use this tube under the temperature range of 5 - 35℃(41 - 95 ).
3. Use this tube under the relative humidity range of 20 - 90%.
4. This tube may be interfered with by the coexisting gases. Please refer to the "INTERFERECES".
5. Shelf life and storage condition of the tube is marked on the label of the box of tube.
APPLICATION OF THE TUBE :
Use this tube for the detection of Formaldehyde in air of environmental atmospheric condition.
SPECIFICATION : (As a result of Gastec's commitment to continued improvement, specifications
are subject to change without notice.)
Measuring Range 0.02 - 0.4 ppm
Sampling Rate 200 mL/min
Correction Factor
Sampling Time
Detection Limit
Colour Change
Formaldehyde reacts with reagent to produce intermediate product which
Reaction Principle
discolours indicator to pink
Coefficient of Variation: 10%(for 0.02 to 0.1 ppm), 5%(for 0.1 to 0.4 ppm)
** Shelf Life: Please refer to the Validity Date printed on the box of tube.
** Store the tubes in the refrigerator to keep at 10℃(50 ) or below.
CORRECTION FOR TEMPERATURE, HUMIDITY AND PRESSURE:
Temperature: Correct for temperature by the table below:
NOTES : Use correction table 1 for 30 minutes measurement and use correction table 2 for 10
minutes measurement.
Correction table 1 (30 minutes measurement)
Tips: Apply correction factor in the cell which is ones digit and tens digit of ambient temperature crossing.
For example, if the temperature is 15℃, the correction factor is the number in the cell where "10" row of
tens digit and "5" row of ones digit crossing. In this case, the correction factor is 1.05.
0 1 2
0 − − −
Tens
10 1.11 1.10 1.08
digit
20 1.0 0.97 0.94
(℃)
30 0.77 0.75 0.74
Detecting layer
0.4 - 1.44 ppm
200 mL/min
1 3.6
30 min 10 min
0.01 ppm
Yellow → Pink
Ones digit(℃)
3 4 5 6 7 8
− − 1.38 1.29 1.23 1.18
1.07 1.06 1.05 1.04 1.04 1.03
0.91 0.88 0.85 0.83 0.81 0.80
0.72 0.71 0.70 − − −
Tube reading
(ppm)
0.02
0.04
0.06
0.08
0.10
0.15
0.20
0.25
0.30
0.35
0.40
41
℃ 5.0
55
℃ 12.8
69
℃ 20.6
83
℃ 28.3
Humidity :
Pressure :
MEASUREMENT PROCEDURE :
If automatic air sampler Model GSP-300FT-2 is used
1. Prior to operation please confirm if black colour inlet rubber tube holder is equipped with the sampler.
2. Break both end of the tips of the detector tube by the tube tip holder supplied. Connect the detector
tube to the pump with arrow (
3. Set the flow metre at 200 mL/min and timer to "30 minutes" of the sampler. Press the power switch of
the sampler to start the sampling.
4. After the sampling, remove the detector tube from the sampler.
5. Read the concentration from the length of discoloration of the tube. If the discoloration exceeded the
0.4 ppm level, prepare fresh detector tube. Reset the sampler at flow rate of 200 mL/min and "10
minutes" of the timer and start the sampling again.
6. If correction is needed, after sampling, multiply the correction factor of the temperature, sampling
volume and pressure respectively.
Conversion factor of ppm andμg/m
μg/m
3 = measurement (ppm) ×
30.03 : molecular weight of formaldehyde
22.4(L) : molecular volume at 1bar, 0℃.
273(K) : K is absolute temperature and 0℃ is 273.15K
Thus, t℃ is converted to (273+ t )K
9
1.14
1.02
0.78
−
Correction table 2 (10 minutes measurement)
Temperature Corrected valur (ppm)
10 ℃ 15 ℃ 20 ℃
5 ℃
0.045 0.028 0.022 0.020
0.092 0.058 0.044 0.040
0.144 0.092 0.069 0.060
0.199 0.130 0.095 0.080
0.258 0.171 0.123 0.100
0.281 0.195 0.150
0.415
0.584 0.401 0.272 0.200
0.763 0.531 0.352 0.250
0.949 0.667 0.436 0.300
− 0.855 0.509 0.350
− 1.018 0.593 0.400
Temperature conversion chart
42 43 44 45 46 47 48
5.6 6.1 6.7 7.2 7.8 8.3 8.9
56 57 58 59 60 61 62
13.3 13.9 14.4 15.0 15.6 16.1 16.7
70 71 72 73 74 75 76
21.1 21.7 22.2 22.8 23.3 23.9 24.4
84 85 86 87 88 89 90
28.9 29.4 30.0 30.6 31.1 31.7 32.2
No correction is required for 20 - 90% R.H.
To correct for pressure, multiply by the tube reading by
Tube Reading (ppm) × 1013 (hPa)
――――――――――――――――
Atmospheric Pressure (hPa)
) on the tube pointing toward pump.
3
30.03 273
× × 1000
− − − − − − −
22.4 (273+ t )
25 ℃ 30 ℃ 35 ℃
0.018 0.017 0.016
0.036 0.034 0.032
0.054 0.051 0.048
0.072 0.068 0.064
0.090 0.085 0.080
0.135 0.128 0.120
0.180 0.170 0.160
0.225 0.213 0.200
0.270 0.255 0.240
0.315 0.298 0.280
0.360 0.340 0.320
49 50 51 52 53 54
9.4 10.0 10.6 11.1 11.7 12.2
63 64 65 66 67 68
17.2 17.8 18.3 18.9 19.4 20.0
77 78 79 80 81 82
25.0 25.6 26.1 26.7 27.2 27.8
91 92 93 94 95
32.8 33.3 33.9 34.4 35.0