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The AlphaLab Air Ion Counter is a handheld meter designed to measure ion density-- the number of ions in air per cubic centimeter (ions/cc). The resistivity of air (6x1018/N in ohm cm if N is in ions/cc) and the discharge half-life of charged objects (in seconds, half-life is 1.2x105/N) can also be determined directly from the readings. It measures both positive and negative ions, and displays them separately. This instrument is a true ion density meter, based on a "Gerdien Tube" design. It contains a calibrated fan which pulls air through the meter; then the ions are detected. It compensates for winds up to +/- 15 km/hour (9 mph). Accuracy is +/- 25% of the reading within the range -10 to +50C (14 to 122F), and air speeds up to 15 km/hour. (Meter accuracy is +/- 3%, but precise ion readings are difficult due to external conditions. Some ions or ion pairs are destroyed when forced to change direction or travel through a hole. This destruction causes slightly over 20% uncertainty in the actual number of ions/cc arriving at the meter. The calibration of the meter is set to give +/- 25% accuracy over all conditions up to 15 km/hr air speed.) The display is in units of 1000 ions/cc, so that a displayed reading of "- 0.60" represents 600 +/-150 negative ions/cc. The meter has three ranges, and it measures up to 1,999,000 ions/cubic cm (essentially 2 million) with minimum resolution 10 ions/cc. All normal natural sources are well within that range, but if you are measuring the output immediately in front of an ionizer, the ion number density may be as high as 20 million ions/cubic cm. Therefore, for ionizer measurements, request the 20 million version. (It is the same price as the standard 2 million ions/cc version, but minimum resolution is 100 ions/cc. A 200 million ions/cc version is also available).
At $390 USD, it is the lowest-priced true ion density meter available. It also is very fast at making measurements, with a one-second response time and a low 10 ions/cubic cm noise level. (For comparison, typical outdoor ion density is 200 to 1000 ions/cc, both positive and negative ions, with more negative ions in areas near evaporating water.) Although it only performs one function--ion measurement-- this meter is very good at that function, with ultra low-noise circuitry and an intuitive design. For anti-static applications, it rapidly determines ion density and balance and can replace a "charge plate detector". Both negative and positive discharge times can be measured in seconds (compared to minutes required by a charge plate detector.) Options include a high-capacity rechargeable battery system and a configuration for long-term data collection. These meters are usually shipped within one business day, and are manufactured by Alphalab, Inc. in Salt Lake City (USA). Warranty is one year.
The Air Ion Counter operates by first pulling air through at a rate of 400 cc/sec. The outer case and the "wind guard" (at the top of the photo) are electrically conductive to shield the sensitive ion detector plate inside from stray static electricity signals. As the air flows around the 5x6 cm detector plate (flow is parallel to the plate), the air is polarized with an electric field of 2500 V/m. The electric field direction is set by the "POLARITY" switch. If set at "+", then positive ions are attracted to the plate, and they give up their charges when they hit the plate. (If set at "-" , then the plate will attract negative ions.) The plate is connected to a sensitive electric current meter, and the amount of current is proportional to the number of electric charges per second that are colliding with the plate. The minimum resolution of 10 ions/cc corresponds to only 8x10-16 of an amp (0.8 femtoamp). Proper mechanical and electrical design (including filtering) keep noise to a minimum.-
External air movement (wind) can cause inaccuracy in ion density meter readings. The Air Ion Counter compensates for wind with the detector plate and polarizing field design. In still air, it is designed so that only 60% of the ions are collected. If there is a wind that pushes air through the meter faster than the normal speed, then more ions per second will be traveling through the meter. This effect would make the meter read too high, but because of the design, the collection fraction drops below 60% if the air flow is faster than normal; the collection fraction increases above 60% if the air flow through the meter is slower than normal, i.e., if wind is blowing into the back of the meter. The net effect is that the Air Ion Counter stays within +/- 25% accuracy in up to 15 km/hr wind in any direction. (For faster air speed, the meter should either be partially shielded or held perpendicular to the wind).
This meter can measure the distribution and velocity of ions as they move through the air. These measurements are essential when setting up uniform ion coverage throughout an area. Unexpected ion sources (radon, leaking combustion vapors, electric arcing, etc.) can also be identified and measured. Because of the fast response time, the time required for ions to reach a location (after the ion source is turned on) can be determined, as well as the time-to-saturation and the lifetime (after the source is turned off). Of course the meter can also measure the ambient ion density, indoors and out. (Note that + and - ions often coexist, and the Air Ion Counter will read both). Whenever you have questions, you can always consult the ion measurement experts at AlphaLab (no charge) for advice on measurements and the physics of ions.
A rechargeable battery system is an option. The meter normally comes with a standard 9V alkaline battery, which lasts about 2 hours of measurement time (at maximum current drain, with the fan on). An option (see below) is a 9V Li-Ion battery with a charger that also powers the meter whenever it is plugged in. The Li-Ion battery will last about 6 hours per charge at maximum drain and has a lifetime of 500-1000 charges. Full charge time is 3 hours, but the charger can remain plugged in for an unlimited time. Replacement Li-ion batteries are available from AlphaLab and battery stores (about $10).
For long-term automated measurements, such as connection to a data acquisition system, order the third option listed below. Note that the standard version of the Air Ion Counter is optimized for manual use, in that an operator simply holds the standard meter and reads the display (there is not an output jack in the standard version). During use, the standard offset should be manually re-zeroed at least every 30 minutes, and more frequently if the temperature is changing rapidly. (Temperature changes of over 5C only affect the offset, but not the sensitivity.) This standard system works well for quick manual measurement of ions, but it is not suitable if automated measurements are collected continuously for weeks or months. Although the Air Ion Counter can run continuously for years (if the inlet is kept clean enough not to block the air flow), this long-term operation requires external power (AC adaptor) and it needs different type of "re-zero". These are both provided by the third option. With this option, the meter can also be operated manually, because it includes an alkaline battery (which is not rechargeable, and the included AC adaptor does not recharge batteries). If a rechargeable battery is required, also order the first or second option.
Air Ion Counter: $390 (US dollars). We will send the standard "2 million ions/cc" range unless you request 20 million. Whichever range you choose can be exchanged for the other range (no additional charge) if you inform us within 30 days of receiving the meter.
Options:
Rechargeable Li-Ion Battery and universal 100-260 V AC Adaptor/Charger that plugs into the meter: +$60
Configured with Output Jack and Long-Term Offset Control, AC Powered (specify 120 or 220 VAC): +$45
Shipping:
Shipping to US: Free (UPS ground from Salt Lake City or Priority Mail, if requested. Other options are available.)
Shipping to Canada (GST must be paid when delivered): +$20
Shipping to all other areas (VAT, GST or import tax is not included): +$40
For sales to China, click here.
For information or to place an order :
Toll free (USA and Canada) 1-800-658-7030
Telephone +1-801-487-9492
Fax +1-801-487-3877
E-mail mail@trifield.com
To place an online secure order, go to DetectorTechnologies.com
Both TriField.com and DetectorTechnologies.com are owned by
AlphaLab, Inc. / 3005 South 300
West / Salt Lake City UT 84115 USA