Subject: Re: Help ! Horicultural Equipment

From: [email-masked] (Robert Harris Stoertz)
Date: Wed, 31 Jul 1996 16:42:00 GMT

@hursley.ibm.com wrote:

>Help please ! I need to quickly find out how to use the following. So far I've been
>unable to find any refs to them. ANY hints, tips, references would be greatly
>appreciated.		
>	Draeger universal gas detector (for CO2)
Don't know how this one works, but an inexpensive gas detector often
has a detector cell, that may be expendable. The reading is often in
parts per million (ppm). If you are doing Internet searches, try
looking for "gas analyzer" (and "analyser"). 
>        Whirling hygrometer
Same as a "sling psychrometer", I think. This measures relative
humidity and dewpoint.
This instrument has two thermometers. A wick keeps one wet. The water
reservoir should be filled and the wick should cover the bulb of the
wet thermometer. The instrument is unfolded like nun-chuks and spun
steadily in the air until the two thermometer readings have stabilized
(usually about 30 seconds). Then the two readings are noted. Read the
wet thermometer first, quickly, because it will start to warm up
immediately. Some of these instruments will have a nomograph printed
directly on the instrument. Otherwise, there should be a nomograph on
a piece of paper in the box. Wherever, the principle is the same---lay
a straightedge from the temperature of the dry thermometer to the
temperature of the wet thermometer. There will be a third scale, on
which you can read the relative humidity in percent, usually. But
usually there is just a slide-rule that slides up along the
thermometers to match the wet reading, I think (it will probably say
which to match). Then you find the dry reading on a built-in scale and
read the humidity and dewpoint that you will find next to it.
>        Megatron light meter
Don't know too much about this, but you'll want to be clear on some
terms, I suspect. I can't find the book I need for this right now, but
remember that intensity and luminosity are different. Lumens are a
measure of how much light is given out by a light source, I think,
while intensity is how much you measure, in foot-candles. Measured
intensity depends on distance, and is used to calculate lumens, which
are absolute. One lumen is the same as one candle-power, I think.
There will be a range switch. The instrument will probably measure
>from  0 to 1000 foot-candles or as much as 0 to 20,000 foot-candles of
illumination.
>        Conductivity meter
Probably the same as a resistivity meter.
In a horticultural operation, this is used to measure resistivity of
water. There is probably a cell on the end of a cable that is immersed
in the water. In a big operation, the cell is probably permanently
mounted in a pipe or a tank, maybe at the outlet of a purification
process or in the incoming water to the hoticultural operation. There
may be a digital readout or an analog readout. In addition, you may
need to turn some range switches to get the reading on scale. These
instruments are used to determine water purity. The higher the
reading, the more pure the water. They may disconnect the meter by
unplugging it from the cell and move the instrument on to a different
cell somewhere else. If so, it should be turned off before unplugging.
The instrument probably has a peak resitivity reading of 5 to 20
megohm-centimeters. The "centimeter" is important---don't leave it
out.

>Thank you, in advance. Barry

I'm guessing you are applying for a job in a horticultural laboratory
or something like that.
If so, good luck.
Regards, Robert

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From: @hursley.ibm.com
Date: 31 Jul 1996 07:32:19 GMT