Fieldpiece ACM3 User Manual

Carbon Monoxide
Accessory Head
Model: ACM3

OPERATOR’S MANUAL

Description

The model ACM3 carbon monoxide accessory
head enables most digital multimeters to measure
low levels of carbon monoxide in parts per million
(PPM). It is intended to measure levels of CO in still
ambient air. In many cases, it can help pinpoint
sources of CO.

It uses a catalytic chemical sensor that con­sumes no chemicals. Life is primarily determined by
the type of exposure.

The most practical application is to determine if
the indoor CO levels are higher than outdoor levels
and to determine the source. This instrument
detects changes in CO levels very quickly.

"Walk around" test

The ACM3 is fast enough to respond almost
instaneously to changes in CO levels in the air. If
you see a difference in CO levels from outside to
inside, you need to find the source of the CO. Walk
around and watch the display. By constantly going
towards the area of highest concentration, you can
determine the source of the CO. It may be that
someone just drove their car into the garage and
opened the kitchen door and you don't have to take
any action. Or it could be that the furnace is starved
for air and that CO is entering the house. You've got
to fix that.

How to use

1. Connect to COM and Volts jacks using the
Fieldpiece deluxe test leads. For Fieldpiece
“stick” meter, slide the head directly over the
meter.

2. Select the 2000mVDC range.

3. Turn on. Let stabilize 45 seconds.

4. Take the instrument outside and adjust it to
zero. Then bring inside to take measurements.

5. Expose sensor to a still, stable air sample (see
precautions). The display reacts to the presence
of CO in seconds. Take final reading when
reading stabilizes.

6. For initial tests, walk around the building, watch­ing for the readings to go up to determine where
maximum concentrations of CO are. To meas­ure air from register, use a pump or measure
out of the air stream. Hot blowing air can
adversely affect the reading. The temperature of
the sample must be near ambient.

Zero adjust

As needed, adjust reading to zero in a known

zero CO atmosphere and in temperature similar to
the sample air to be tested and when ambient air is
within specifications and head is in equilibrium
(temperature and relative humidity) with ambient.

Specifications

Range: 0 to 1000PPM (2000PPM with 5 minute

max exposure time.)

Initial accuracy:

0-15ppm ±5% reading ±1 ppm after zeroing
15-35ppm ±5% reading ±2 ppm after zeroing
0-1000ppm ±5% reading ±5ppm after zeroing

Accuracy: Stated accuracy at 73ºF±9ºF, <90%

relative humidity

Response time: <70sec to 90% of reading
Operating temperature: 32 to 105 ºF
Operating relative humidity: 15 to 90%RH, non-

condensing

Storage temperature: -4ºF to 140ºF, 0 to 80%

R.H. with battery removed from meter.

Long term drift: <5% / year (depending on use)
Sensor calibration: Factory calibrated on

205ppm

Sensor type: Electrochemical (specific to CO)
Battery life: 200 hours typical. No measurable

current draw when in "off" position.

Battery: 9V

Average switch

The average switch averages the readings over
the last two or three seconds. This allows the user
to read more stable measurements.

CO detectors and cracked heat
exchangers

A CO detector cannot tell you if a heat exchang­er is good. A CO detector can indicate a heat
exchanger maybe be cracked only if all of the fol­lowing conditions occur simultaneously:

1. The flame generates high concentrations of CO

(lack of oxygen, excess fuel, high temp).

2. Enough exhaust gases are emitted from the

heat exchanger crack.

3. The exhaust gases from the crack are not dilut-

ed too much before coming in contact with the

sensor. A cracked heat exchanger may leak CO

in a small stream. You may measure high con-

centrations at one point but low concentrations

only an inch away.

4. The heat exchanger is the only possible source

for the CO detected.

Precautions

1. Do not measure gas engine exhaust or other
high CO or highly contaminated gases. High
levels of CO and other contaminants can ruin
the sensor.

2. Do not take readings directly in stream of air at
register or in a flue.

3. Allow enough time for accessory head to reach
ambient temperature and RH%.

Air being measured must be stable and between

32ºF and 105ºF and 15%RH and 90 %RH.
Temperature and humidity changes can cause tran­sient readings. For best results, use a AOXP2 pump
to sample the air, cool it to near room temperature,
and raise the relative humidity.

CO exposure effects

Effects can vary significantly depending on

age, sex, weight, and overall health.

Coffee cup test

To demonstrate that your CO head works, turn a
ceramic coffee cup upside down and slide it over
the edge of a counter (or desk) to expose about a
third of the mouth of the cup. Burn a cigarette
lighter inside the exposed mouth of the cup. Don't
burn the counter. When the flame starts to flicker,
you've burned up most of the oxygen in the cup cre­ating carbon dioxide and now you're starting to pro­duce CO (carbon monoxide). Bring the flame in and
out of the mouth of the coffee cup to just keep the
flame alive. The longer you keep the flame flicker­ing, the more CO you produce. After 10 seconds of
flickering, extinguish the flame and put the CO head
in the mouth of the cup. You should see readings in
the 100s. Take it out if it approaches 1000PPM.

CO ppm Effects

9 ppm

Minimal. Max allowable concentration
for eight hours (EPA and ASHRAE).

35 ppm

Max for continuous expos ure for one
hour (EPA and ASHRAE).

50 ppm Max for eight hours (OSHA).

100 ppm

Trips installed CO detect ors. UL2034
specifies a max exposure of 100 min.

200 ppm

In two to three hours: s light
headache, tiredness, dizz iness,
nausea. UL2034 specifies a max
exposure of 35 min.

400 ppm

In one or two hours: frontal
headaches. In three hours: life
threatening. UL2034 specifies a max
exposure of 15 minutes .

800 ppm

In forty five minutes: dizzines s,
nausea, and convulsions.

800 ppm In two to three hours: deat h.

1600 ppm In one hour: death.

6400 ppm In fifteen minutes: deat h.

12800 ppm In three minutes : death.

WARNING

Do not take measurements directly at a
tailpipe, in a furnace flue, or at a register. See
precautions.

Do not rely solely on a carbon monoxide
measurement to determine if a heat exchanger
is bad. See paragraph on left.

!

!

Storage

Do not store in areas which contain solvent
vapors. This includes aerosols such as air-freshen­er, wax polish, window cleaner, and all organic sol­vents.

Calibration

Because the chemical sensor can be degraded
by exposure to harmful chemicals, dirt and other
contamination, high temperatures, and extremes in
humidity, periodic calibration can maintain accuracy
of the sensor over time. Drift is expected to be less
than 5%/year in most cases but is dependent on
use.

Optional pump

Use the model AOXP2 pump to extract ambient
air samples from hard to reach places or from loca­tions where the air temperature is high.

For potentially high concentrations of CO, pump
slowly and stop if the measurement approaches
2000PPM.

Carbon monoxide concentrations will begin to be
shown in two or three squeezes. For final reading,
pump until the reading stabilizes--approximately 30
squeezes.

Press MAX on DMM to hold highest reading.

AOXP2

Connect ACM3 in multiple ways

EHDL1 HS series AHDL1 w/ Meter

Cross-sensitivity

The sensor has a permanent unreplaceable filter
built inside the sensor to filter out trace concentra­tions of SO2, NO2, and most hydrocarbons. If
exposed to high concentrations of harmful chemi­cals or dirt, the filter can deteriorate and/or impede
diffusion of air to the sensor.

One Year Limited Warranty

This head is warranted to the original purchaser
against defects in material and workmanship for a
period of one year from the date of purchase.
During the warranty period, Fieldpiece will replace
or repair the defective unit, subject to verification of
the defect.

Any damage to the sensor from dirt, mechanical
abuse, or overexposure to damaging chemicals,
including overexposure to carbon monoxide, are
not covered under this warranty. Also not covered
are defects resulting from abuse, neglect, accident,
unauthorized repair, alteration, or unreasonable
use.

ANY IMPLIED WARRANTIES ARISING OUT OF
THE SALE OF A FIELDPIECE INSTRUMENT
PRODUCT, INCLUDING BUT NOT LIMITED TO
IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE,
ARE LIMITED TO THE ABOVE. FIELDPIECE
SHALL NOT BE LIABLE FOR LOSS OF USE OF
THE INSTRUMENT OR OTHER INCIDENTAL OR
CONSEQUENTIAL DAMAGES, EXPENSES, OR
ECONOMIC LOSS, OR FOR ANY CLAIM OR
CLAIMS FOR SUCH DAMAGE, EXPENSES, OR
ECONOMIC LOSS.

Local laws vary. Above limitations or exclusions
may not apply to you. This warranty gives you spe­cific legal rights, and you may also have other rights
which vary by location.

Service

Return any defective ACM3 to Fieldpiece for war­ranty service along with proof of purchase. Contact
Fieldpiece for out of warranty repair charges.

Fieldpiece Instruments, Inc.

California, U.S.A.

www.fieldpiece.com

Gas PPM

Cr oss

sensitivity %

Hydrogen

sulfide

207 1.3

Sulphur

dioxide

208 -0.7

Nitric

oxide

1000 46

Nitrogen

dioxide

20 -4.4

Chlorine 15 -3.8

Hydrogen 200 78

Hydrogen

cyanide

15 -0.5

Hydrogen

chloride

135 -0.7

Removable rubber strip

Use your calibration tool that comes with the

ACM3 to zero adjust.

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