Fumiscope Version 4.2

Operating Instructions

Purpose and Principles of Operation October 2001 Patented

The fumiscope is a portable instrument which will measure the concentration of gases in the air. The instrument is calibrated for the measurement of Methyl Bromide and Vikane gases in the range of concentration used in fumigations for insect pest. The display indicates the concentration of these fumigant gases in dry air to an accuracy of 2 percent of the full scale reading, in the range from 0- 1999 oz.per 1000 cu.ft. of Methyl Bromide or Vikane.

( oz.per 1000 cu.ft. is the same as metric readings)

The fumiscope employs a thermal conductivity cell to compare the thermal conductivity of a mixture of gas and dry to that of ambient air. The difference is converted into an electric current which represents the concentration of the fumigant and it shown on the digital display. The fumiscope contains of power supply for operation from a 115 volt A. C. line. (220 volt available) The fumiscope also contains an electric pump and gas flow meter so the gas sample can be drawn through the T/C cell at a controlled rate.

The Flow rate of the sample stream may be adjusted to a constant value, regardless of the length of the sample tubing by the flow adjustment knob. A line filter is placed in the gas sample line to prevent water and dirt from entering the instrument. The fumiscope, being a portable instrument, requires no more than a level place to set the instrument and grounded power source. The power requirement for the fumiscope is only 200 watts, so a small inverter can be used to increase instrument portability. The Fumiscope is complete in one case and requires no other auxiliary equipment. 

Inlet – The hose connection is the connection for the sample line to connect to the instrument through the line filter.
A ผ “I.D. vinly sample line should be used and NO adapters or couplings should be used.

Digital Display – The digital display registers the concentration in oz.per 1000 cu.ft. There is no need to convert readings, however, 1 oz. = approximately 250 ppm.

Fumigant Selector Switch – As Marked by MeBr and Vikane this switch changes the display to register the concentration of the selected gas.

Zero adjust knob – This adjustment is used to bring the display to read Zero after the instrument has warmed up and settled. The instrument should be set to zero before taking reading and reset after each reading.

Line Switch – The line switch is separate from the pump switch so the instrument can be turned on and warmed up or left on. The instrument can be left on for long periods without harm, in fact, it is beneficial to do so.

Fuse – The instrument is protected by a fuse which is accessible from the front panel. If replacement is necessary use only “Little fuse or Bussman # AG – 3, 3 amp fuse.

Exhaust – An outlet fitting is provided to return exhausted gases back to the fumigation chamber. This is recommended when the instrument is used in confined spaces. When used outdoors this may not be necessary, however it is recommended the exhaust be directed away from the operator.

Flow Meter – The flow meter indicates the amount of gas sample being drawn through the unit. The flow meter should always be set to the # 1. This is the flow rate that is used to calibrate all Fumiscopes. The meter may need to adjusted after sample line are attached and disconnected. The Flow meter should always read 1.. Occasionally the flow meter ball may stick. A gentle tap may be necessary to dislodge the ball.

Flow rate adjustment – This knob adjust the flow rate of the flow meter. The flow rate should ALWAYS read 1.0.

Operation – When using the fumiscope to monitor the gas concentration during a fumigations it is set up in a location outside the area to be fumigated but easily accessible to the operator and the line source of power and light.

The sample tubing used is ผ”I.D. polyvinyl tubing. Clear tubing is used so that it may be inspected for dirt and water. If either is present do NOT use the tubing. The tubing should be clean and dry. Water will damage the Fumiscope. The sample tubing should be placed at some point in the fumigation area that the fumigator feels will best represent the whole fumigation area. Frequently, several tubes are used to monitor the gas concentration various locations within the fumigation area to check the distribution of the gas.

When all is set up, the fumiscope should be turned on and allowed to warm up. This should take about 3-5 minutes. It is recommended the fumiscope be kept at the same temperature as the fumigated sight. It may take up to 2 hours for the fumiscope to acclimate if moved and extreme temperature. Warm up can be accomplished with the pump switch in the off position. The pump should be turned on after warm up and the display allowed to settle. After the displays settles the flow meter should be set to the #1 and the display should be set to Zero. The fumiscope is now ready to take readings.

After the gas has been introduced and allowed to come to equilibrium, connect the sample tube to the filter and allow the pump to draw a sample into the Fumiscope. This may take a few minutes depending on the length of the sample tubing.
Wait until the instrument reaches its maximum reading (less than 5 minutes). Make sure the flow meter is on 1 with the tube connected. When the sample tube is disconnected the instrument should return to Zero. Again check the flow meter (1). If necessary re-zero the instrument before taking additional readings.

Measuring other gases – The fumiscope can be calibrated to measure other gases, Carboxide can be read on the Vikane scale without having the instrument re – calibrated.

Maintenance – The line filter should be clean and dry. Replace the filter if the flow rate of #1 can not be obtained or moisture is presents. This will extend the life and calibration of the Fumiscope.

Avoid letting any water or dirt to enter the unit. Check the sample tubing to be sure there is no moisture in the lines. It is advisable to run the Fumiscope before going to the fumigation job. Let the instrument run for several hours, especially if the unit has not been operated for long periods of time.

Returns – Most damage is done in shipping. We suggest letting a professional shipping company pack the instrument for return. We MUST HAVE a return shipping address 
( NO PO.BOXES) and a name and contact phone number with area code.

Note: The Fumiscope has been up-dated ad of October 2001. The new instruments no longer required the use of Drierite. Older instruments can be upgraded to this new patented technology.


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