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Re: [APD] Extech Instruments pH probes


I used to use Extech pH probes at my work for continuous pH monitoring of 
the discharge to the sewer authority. They were in water with a pH of about 
9.5 in a flow of about 3,000 to 4,000 gallons per day. We were required to 
do a three point calibration of the probe weekly and it very seldom drifted 
any more than 0.1 pH unit in a week. I have had their probes last for a year 
without needing to replace them. They were gel filled with a plastic guard 
around the glass bulb of the probe. (Remember that the glass is very fragile 
and easily broken.) I didn't want to be bothered with the refillable probes.

We purchased a water recycling system to reduce water use and no longer 
discharge continuously and no longer need to monitor continuously. Extech's 
probes were cheaper than the name brand probes and had equal quality in my 
experiance and opinion. I would use them again if I had a similar need.

I would think the greatest problem in a hot humid climate is oxidation of 
the connector between the meter and the probe. The probes I used were 
waterproof. Keep the probe in a suitable electrode storage solution between 
uses and you will be able to use it for a long time as long as you don't 
crack it.

I have used a contact cleaner sold by Caig Laboratories in San Diego, CA, 
USA www.caig.com called DeoxIT D5 along with PreservIT. These both work 
great in my opinion- No connection with them also. Many years ago when I 
still had vinyl LP records I sprayed the connections between the amplifier 
and the turntable including the wires in the tone arm connecting to the 
stylus. I played an album of Bach Toccatas and Fugues by E. Power Biggs on 
the organ. I was amazed because I heard the sound of the mechanism in the 
organ which connected the keys to the pipes of the organ. I had never heard 
them before cleaning the contacts. I also cleaned the pins on my fluorescent 
lamps and connectors in the reflector because the lamp wouldn't start easily 
without moving it. Fixed it perfectly.

Jerry Smith in Bloomingdale, NJ, USA where it is raining with the remains of 
Hurricane Wilma.

>Date: Sun, 23 Oct 2005 06:59:39 +0930
>From: Dave Wilson <aqua_green at bigpond.com>
>Subject: [APD] Extech Instruments pH probes

>Is there anyone who has had any experience with Extech pH probes.   There 
>a model offered that has a refillable probe.   I was wondering how they
>perform in a hot humid tropical environment.   Here it in NT of Oz is hot
>all the time and very humid for about 4 months.   Most of the pH pocket 
>probes I have tried over the years seem to die just after the warranty runs
>There is also the manufacturer of the products web page
>Dave Wilson

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