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November
1998 Volume 21, Issue 11
A review of Extech Temperature Probes
by Thor
I recently bought a few parts for my homebrewery to make it
easier to monitor the temperature when I'm running a small batch of beer. My current
system requires checking the temperature at several spots in the brewing process. These
are:
The mash tun: To monitor the mash schedule and when I
direct fire the mash liquor with propane for single infusion.
The HLT or Hot Liquor Tank for monitoring the sparge
water
The boil kettle. Its not so important to check it when
its boiling but it helpful if I heat the beginning sparge water here first than transfer
it to the HLT.
The temperature of the finished, chilled beer. I measure
this at the end of the counterflow chiller.
The first three of these containers already have thermal
wells welded in them for ease of temperature probe placement. For those unfamiliar with
thermal wells, they are stainless steel probes that have good thermal properties that are
inserted into the vessel you wish to check the temperature of. They also keep the probe
from contacting the liquid directly.
In addition to fixed temperature meters, I also wanted a
mobile temperature probe that I could check other items from time to time. These would
include things like the temperature of the sparge water coming out of the manifold or for
any other item I hadn't thought of.
I decided to buy my digital thermometers through a local
distributor called Jameco since they had a convenient catalog and I had good luck buying
from them in past. The two products I purchased are described below. I hope to write a
follow up article once I get the probes installed in my brewery to relate how the probes
work in a real brewing environment. In the meanwhile are some of my preliminary findings.
The last item in the list is a new probe, not available at
the time of my order but that looks promising. In a later article, I'll try and review it
as well.
EXTECH Digital Thermometer, Panel Mount
Model TM2000F
(Jameco 151925, $32.95) |
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Easy to read black LCD temperature display with 10 second sample rate.
3.5 digit, 0.6"H display
Uses 1.5V AA battery for easy installation (not included)
Temperature ranges in degrees C and F (0 to 160F; -20 to 70C or -40 to
100C)
Built-in sensor
One-year warranty
Resolution to 0.2F (0.1C) and accurate to plus or minus 1.8F (1C)
Size: 2.9"L x 1.5"W x 0.9"H
Probe length is 30 inches to the base of the unit
Weight: 0.2 lbs.
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| Remarks: I purchased four of these units. Eventhough they are stated to
be without 1.5V batteries, these came with them anyways.
The enclosures seemed pretty rugged and the size of the panel was standard so it fit
into an ordinary panel enclosure. I couldn't find anyway to switch the unit to Celsius
though and currently am trying to find out via the tech help. I later found out that the
meter actually could not be set to Celsius at all and that they had a Celsius version that
your could buy instead. The model number TM-2000C is presumably that version.
The unit is always on unfortunately but the batteries seem to last a long time ( a week
so far). Though it might be a bit of a hassle, I may have to remove the batteries when not
in use so as to not waste them.
Another thing I noticed was that even though the specs say the meters go up to 160 F, I
found that the units gave accurate reading up to 190+ F.
If you look at Extech web site, they have the next generation of this device called the
TM-3000 which has some additional features and an ON/OFF switch. I list the details from
their site for convenience. |
| Pocket Thermometer/Alarm
¦C/¦F switchable with 0.1¦ resolution and audible High/Low Alarms
Model 392085 $29
(Jameco 148814, $34.95) |
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- Audible alarm alerts user when pre-set max or min temperature is reached or exceeded
- Data Hold function freezes temperature reading on display
- Ranges: -58 to 302 °F and -50 to 150 °C
- 0.1 ° resolution from -19.9 to +199.9 °; 1 ° over 200 °
- Accurate to ±1.8 °F from -58 to 212 °F ( ±1 °C from -50 to 100 °C)
- Durable 2.5 " (64mm) stainless steel probe with 20 "(508mm) cable
- Dimensions 4.8x3x8 "(122x76x20mm); Weight 3.4 oz. (96g)
- Probe wire length is 36" long
- Complete with wallet style case, stainless steel probe, and 1.5V button battery
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| Remarks: This item was very easy to use and convenient as well. The
alarm settings took a little reading though since they like to economize on buttons. |
New model. Not yet available but looks better than the TM2000.
Miniature Digital Temperature Indicator °C/°F
Panel Mount Indicator complete with Thermistor Sensor |
Model TM3000, $29 |
Features:
- 3-1/2 Digit (1999 count) LCD with large 0.7 digit height
- Attached temperature sensor with 35 insulated cable
- Audible Hi/Lo temperature alarms
- Temperature range switchable from -58 to 302°F (-50 to 150°C)
- Battery power and attached sensor eliminates wiring concerns
- Snap-in panel mount design eliminates need for screws
- OFF switch preserves battery life
- Complete with one 1.5V battery and thermistor temperature sensor.
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| Specifications |
Range |
Resolution |
Accuracy(%rdg) |
| Temperature measurements: |
-58 to 302°F (-50 to 150°C) |
0.1° from 19.9° to 199.9°, 1° for <19.9° and> 200° |
±1°C (-10°C to 100°C), ±1.8°F (-5.8°F to 212°F), ±2°C or
3.6°F outside these limits |
| Display: |
3-1/2 digit (1999) LCD |
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| Temperature Sensor: |
Thermistor (Insertion type) with 35 cable hardwired to meter |
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| Ambient temperature: |
-50 to 104°F (-10 to 40°C) |
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| Power supply: |
One 1.5V G13 style battery |
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| Dimensions: |
Bezel: 2.44 x 1.4; (61.98 x 35.56mm),
Meter: 2.25 x 1.25 x 0.49D (57.15x31.75x12.45Dmm),
Sensor length: 2.75 (69.85mm) |
Weight: |
1.2oz. (34g) |
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