ECO SENSORS, INC.
Ozone Sensor
MODEL A-21ZX
INSTRUCTIONS FOR USE
GENERAL DESCRIPTION
The model A-21ZX is designed for sensing ozone and for estimating ozone levels in the 0-
10 ppm range. It is not an analyzer, and there is some sensitivity to other oxidizing gases.
Except for special applications, its routine use is only recommended for the 0-1 ppm range.
The instrument can be run over 8 hours from its rechargeable batteries, and it can be run
from AC power as a permanent monitor. Before operating the instrument read all instructions
and the conditional warranty statement in this manual.
OPERATION
Turn the function switch to On. Digits should appear on the readout. After about a minute
the display will show 0.00 or a slightly positive reading. If there are no readout digits, the
batteries are discharged. (For charging, see Battery Operation.) The A-21ZX instrument
can also be used as a permanent monitor in the On position of the function switch using
the charger as a power source. In this case, the average levels of the ozone shouldn’t
exceed .1 ppm to maintain stable readings and to avoid corrosion of the electronics.
Readings above 1 ppm should be brief.
For leak checking, bring the sensor as close as possible to the suspected leak. For
monitoring, orient the instrument so that the sensor is perpendicular to or facing away
from any air flow. If there is air flow into the gas inlet, the readings may be higher than they
should be.
The A-21ZX responsivity slows at temperatures below 50 deg F (15 deg C). To minimize
this, keep the instrument warm by keeping its power on or by storing it in a warm place
until just before use.
Acid gases and certain other conditions cause the instrument’s readings to creep up after
establishing a stable point. Outdoors: operate at above freezing temperatures and during
the day. Semicon fabs, sewage treatment plants, etc.: avoid acid gases and sulfur
compounds. Water treatment plants: avoid strong chlorine concentrations. In general, after
the instrument has reached a stable reading in about a minute, it is best to turn it off or to
remove it to a protected area. A mechanical shock to the instrument can cause it to zero.
It will recover in a few minutes.
CHARGING AND WARM-UP
The A-21ZX charges with the function switch in the on or off position and the AC adapter
plugged in. 14 hours are required for fully discharged batteries.
When not using the
instrument, it is strongly recommended to leave the charger plugged in and the function
switch in the off position. In this mode, the sensor will stay heated. Then if the instrument
is turned on before unplugging the AC charger, the instrument is ready to use immediately.
Otherwise warm-ups are required with a major purpose being to “burn-off” trace chemicals
that the sensor will absorb if it has been idle and not heated. Recommended A-21ZX
warm-up times by either battery or AC adapter are:
Time Since Last Powered
Warm-up Time
1 minute - 3 days
10 minutes
3 - 7 days
1 hour
more than 1 week
24 hours
To minimize warm-up time, check the A-21ZX for full response with our OG-2 Ozone
Source Calibrator.
CALIBRATION
The A-21ZX will read from .01 ppm to over 10 ppm of ozone. Its primary calibration point
is . 1 ppm. Its greatest accuracy - usually 10-20% - extends from .05 ppm to .3 ppm.
Accuracy declines below .04 ppm and above I ppm. The calibration should be checked if
the instrument’s response gets slower, less reactive, or tends to creep up with no apparent
ozone present. The instrument should be recalibrated annually and more often if it is in
constant use. Sensor failure is indicated by a permanent very high reading. (The Eco
Sensors OG-2 .1 ppm UV source can be used for recalibration.)
BATTERY OPERATION
The lo bat light will come on when there are about 10 minutes of use left. The batteries are
a special NiMH design and are not user replaceable. They should last for several years of
daily operation and much longer for occasional operation. To charge, plug in the charger
and turn the function switch to the Off position.
The batteries will require 14 hours (overnight) to recharge and should provide over 8
hours of use from a full charge. A rough guideline is that there are 30 minutes of use
available per hour of charging. The A-21ZX can be recharged in vehicles using 12 volt
output cigarette lighter adapters available from electronic stores (5.5/2.5 mm jack, ).
AC ADAPTER/CHARGER
For North American customers, the instrument is supplied with an adapter design to convert
110- 120 volts 60 Hz: to 12 volts DC at 500 MA. Elsewhere, the adapter must be purchased
locally. Converters from wall voltage to 12 volts DC unregulated with our size DC power
jack (5.5/2.5 mm ) are the most commonly available size worldwide. The actual
output voltage under load of the ’12 volt” adapters varies widely. The A-21ZX will accept
10-18 volts but not 24 volts. See our Tech Note P-101.
SPECIFICATIONS
Sensor: Heated metal oxide semiconductor.
Sensitivity: As low as .02 ppm.
Response time: Within 10’s of seconds
Temperature and humidity range: 32-104 deg F (0-40 deg C) 0-80% relative humidity.
Supply voltage required: 12 volts DC, 300 mA., ctr. + (ground -)
Battery life: Over 8 hours per full charge.
Size of instrument: 2" x 4" x 1" (50 x 100 x 25 mm.).
Weight of instrument: Appx. 6 oz. (170 grams).
Shipping weight, instrument and AC adapter: appx. 1 3/4 lbs. (about 3/4 kg.)
SAFETY FEATURES
Enclosure: Self-extinguishing ABS plastic.
Electrical: (a) Circuits operate at 18 volts 200 mA or less. (b) Automatically resetting fuse
to protect against excess current flow
PRECAUTIONS
• Allow sufficient warm up time.
• Read all instructions in this manual.
• Keep instrument dry. Never let water or other liquids into the sensor.
• Do not drop the instrument or subject it to continuous vibration.
• Do not store in high levels of dust.
• Do not clean the instrument with cleaning chemicals or solvents. Clean it with a damp
cloth or with “Armor All” (R).
• Do not operate near heavy aerosols (spray) usage, where oxygen is being administered,
or in the presence of explosive fumes or gases.
• Avoid “poisoning” the sensor by leaving the Instrument on or in the presence of ozone for
longer than necessary to take a reading of greater than 1 ppm of ozone. Also avoid prolonged
exposure to gases and vapors of halogen and sulfur compounds.
• Do not take readings where the sensor is subject to drafts or breezes.
• Avoid use in below freezing temperatures.
• Avoid excessive pressure on or shock to the glass window of the digital readout.
Call a qualified electrician if you have any doubts about voltages, currents, electrical practice, etc.
LIMITED WARRANTY
This product is warranted against defects in materials and workmanship for one year
following the date of purchase by the original owner. This warranty does not include damage
to the product as a result or misuse, accident, damage, modifications, or alterations, and
it does not apply if the instructions in this manual are not followed.
If a defect develops during the warranty period, Eco Sensors at its election will repair the
instrument or replace it with a new or reconditioned model of equivalent quality In the
event of replacement with a new or reconditioned model, the replacement unit will continue
the warranty of the original model.
To return the instrument contact your distributor, or call Eco Sensors at (800) 472-6626 or
e-mail at: [email protected] to receive return instructions and a Return Goods
Authorization (RGA) number.
Except as provided herein, Eco Sensors makes no warranties, express or implied, including
warranties of merchantability and fitness for a particular purpose. Eco Sensors shall not
be liable for loss of use of this instrument or other incidental or consequential damages,
expenses or economic loss, or claims for such damage or economic loss.
This warranty gives you specific legal rights, and you may also have other rights which
vary from state to state.
RECORD YOUR SERIAL NUMBER HERE __________________________________
KEEP THIS MANUAL AND WARRANTY FOR YOUR RECORDS.
Eco Sensors is a registered trademark of Eco Sensors, Inc.
(c) Eco Sensors, Inc. 2000
Rev. 1/00
OZONE SENSOR
CALIBRATION
ADJUSTMENT ACCESS
DO NOT ALLOW
WATER TO ENTER
MODEL P-20
AC CHARGER
FOR
110-130V.
60 HZ AC
CHARGE OVERNIGHT
FOR 8 HOURS OF
CONTINUOUS OPERATION
CHARGER JACK
12V. 300-500 MA. CTR. +
OFF
FUNCTION SWITCH
ON
LO BAT LIGHT
(Comes on about 10 minutes
before battery discharge)
DIGITAL READOUT
