Common CO2 Gas Analyzer Features (SBA-4, SBA-5, EGM-4 and WMA-4)

Calibration

The design of our CO2 gas analyzers (SBA-4, SBA-5, EGM-4 and WMA-4) ensures an inherent calibration stability that has been confirmed by over 25 years experience in gas analysis technology.  Our analyzers do not require CO2 recalibration (we recommend periodic checks to confirm system integrity).  The analyzers employ a non-dispersive, infrared measurement technique, coupled with microprocessor-based signal processing to achieve excellent stability and specificity to CO2.  Our innovative "Auto-Zero" technology ensures fast warm-up, long term stability, accuracy and analyzer calibration. It also minimizes the effects on span (gas sensitivity) of sample cell contamination, source aging, changes in detector sensitivity and changes in pre-amplifier gain.

Measurement Ranges

All CO2 gas analyzers can be supplied with two different optical benches.  One bench is designed for measurement of CO2 in the ranges of 0-1,000 ppm up to 0-30,000 ppm and another optimized for 0-50,000 ppm and 0-100,000 ppm  For users that want to recalibrate the gas analyzer to a new level, this can easily be achieved as long as it is within the range for that particular optical bench.

Flexible, Versatile User Interface

Our analyzers are extremely powerful and versatile instruments.  A range of accessories can be used with our gas analyzers enhancing measurement capability.  Refer to the table below to see which accessories are compatible with the SBA-4, SBA-5, EGM-4 and WMA-4.

Software

Most PP Systems' analyzers are supplied with a Windows^® based software program for transferring and logging sensor data (not available for use with SBA-5 at this time). The sensor data may be recorded manually or automatically depending on user specified settings. Stored records (ASCII) can be later imported into your favorite spreadsheet program for further analysis.

On-line help is available to guide you every step of the way.

Product Specification

Specification	SBA-4	SBA-5	EGM-4	WMA-4
Analysis Method Non-dispersive infrared configured as an absolute absorptiometer with microprocessor control of linearization.	Ö	Ö	Ö	Ö
Measurement Ranges 0-1,000 ppm (µmol mol-1) 0-2,000 ppm (µmol mol-1) 0-5,000 ppm (µmol mol-1) 0-10,000 ppm (µmol mol-1) 0-20,000 ppm (µmol mol-1) 0-30,000 ppm (µmol mol-1) 0-50,000 ppm (µmol mol-1) 0-100,000 ppm (µmol mol-1) Custom ranges up to 100,000 ppm upon request.	Ö	Ö	Ö	Ö
Automatic temperature & pressure compensation	Ö	Ö	Ö	Ö
Accuracy < 1% of span concentration over the calibrated range, but limited by the accuracy of the calibration gas mixture	Ö	Ö	Ö	Ö
Linearity < 1% throughout the range.	Ö	Ö	Ö	Ö
Stability Automatic zero at regular intervals, corrects for sample cell contamination, source and detector ageing and pre-amplifier gain changes.	Ö	Ö	Ö	Ö
Sampling Pump	Optional Also requires an electrical kit.	Optional	Integral 6V DC Pump	Integral 12V AC Pump
Flow Rate	200-500 ml/min recommended	200-500 ml/min recommended	Fixed at 350 ml/min (Approximate)	Adjustable from 200-1,000 ml/min
Flow Meter	No	No	No	Yes
Environmental Sensor Inputs	5 input channels (connection through terminal block)	1 input channel(connection through terminal block)	2 input/output connectors (15 pin)	5 input channels (connection through terminal block)
Air Filter	Optional	Optional	Filtered sample line (hydrophobic)	Filtered sample line (hydrophobic) with water trap
Calibration Default value preset in factory (built-in linearization).	Potentiometer adjustment	User programmable	Calibration through keypad	Calibration through keypad
CO2 Control High and low set points.	Not available	Not available	Ö	Ö
Alarm	Not available	Not available	Visual and audio	Visual (LED) and audio
Real Time Clock Accuracy > 1 minute per month at 25o C, operating temperature 0-70o C.  Automatic correction for month end and leap years.	Not available	Not available	Ö	Ö
Recording Manual (by key press) or automatic at user selected intervals between 1 and 250 minutes.	Not available	Not available	Ö	Ö
Data Storage	Not available	Not available	512K Battery backed RAM (1,000 records)	512K Battery backed RAM (1,250 records)
Response Time Display/Analog Output: 1.6 seconds	Ö	Ö	Ö	Ö
Analog Output (CO2 only) 4-20 mA, 0-1V, 0-2V, 0-3V, 0-4V, 0-5V (linear)	Ö	Dual 0-5V linear (CO2 and H2O) 4-20 mA (CO2 only)	Ö	Ö
Digital (RS232) Output 9600 baud/8 data bits, 1 start bit/2 stop bits/no parity.  ASCII format.	Ö	Ö Also includes USB	Ö	Ö
Windows Software	Ö	Not available	Ö	Ö
Display High contrast, 2 x 16 character LCD	No display	No display	Ö	Ö
Power Supply	12 VDC (User supplied)	6-18 VDC (user supplied)	12V, 2.0 Ah lead acid or 12V NiMH rechargeable battery	85V AC - 264V AC (47 Hz - 63 Hz) or 12V DC
Power Consumption	12V@ 0.7A (warm-up) 12V@ 0.5A (normal operation)	8 W (warm up) 1-3 W (Normal operation and dependent on ambient temperature)	12V @ 0.7A (warm-up) 12V @ 0.4A (normal operation)	115V @ .15A (maximum) 230V @ .075A (maximum) 12V @ 1.3A (maximum), 0.75A (normal operation)
Gas Connections Two barbed fittings (inlet and exhaust) for use with 1/8" (.125") ID tubing	Ö	Ö	Ö	Ö
Housing	None.  Supplied as board only (PCB Type FR4)	None.  Supplied as board only (PCB Type FR4). Optional aluminum enclosure is available (TBD).	High impact, aluminum enclosure	High impact, IP65 enclosure
Dimensions	15.5 cm (W) x 17 cm (L) x 3 cm (H)	7.5 cm (W) x 12 cm (L) x 3.5 cm (H)	18 cm (W) x 21.5 cm (H) x 6.3 cm (D)	23 cm (W) x 15 cm (H) x 14 cm (D)
Weight	0.3 kg	0.2 kg	1.9 kg	1.9 kg
Accessory Compatibility	SBA-4	SBA-5	EGM-4	WMA-4
SRC-1 Soil Respiration Chamber	Not compatible	Not compatible	Ö	Not compatible
STP-1 Soil Temperature Probe	Not compatible	Not compatible	Ö	Not compatible
CPY-2 & CPY-4 Canopy Assimilation Chamber	Not compatible	Not compatible	Ö	Not compatible
PMR-5 Steady State Porometer	Not compatible	Not compatible	Ö	Not compatible
Humidity Sensor	Ö	Ö	Ö	Ö
PAR-1 Probe & PAR Sensor	Ö	Ö	Ö	Ö
TRP-1 & TRP-2 Temperature/PAR Probe	Ö	Ö	Ö	Ö
OP-1 & OP-2 Oxygen Sensor	Ö	Ö	Ö	Ö
	SBA-4 Data Sheet		EGM-4 Data Sheet	WMA-4 Data Sheet

PP Systems is continuously updating its products and reserves the right to amend product specifications without notice.

Auto-Zero

All PP Systems' CO2 infra-red gas analyzers feature the Auto-Zero facility. This feature, which occurs at regular intervals, allows for fast warm-up, adaptation to changing ambient conditions and excellent stability of the CO2 signal. The action of auto zeroing minimizes the effects on span (gas sensitivity) of sample cell contamination, source aging, changes in detector sensitivity and changes in pre-amplifier gain.

Our company considered using a 2 wavelength detector several years ago, but concluded that true auto zero instruments such as ours provided greater stability and reliability for the following reasons:

• Major effects of temperature are on the transmission characteristics of the interference filters and in 2 wavelength instruments, these are required to closely track.
• Dirt in the cells, changes in cell reflectivity, changes in source position or relative emission over the source surface can differentially affect the sensors.
• Changes in source temperature will affect the relative emissions at the two wavelengths.
• Cross sensitivity problems to other gases are increased as neither wavelength must be affected.
• Both sensors will require electronics and these must have identical temperature coefficients and must age exactly the same.
• Reliability must decline as the component count increases.
• Using two sensors degrades the signal/noise which is inversely proportional to the sensor area.

The only disadvantages to the auto zero approach is that the analyzer requires a flow, a solenoid valve and a chemical absorber (soda lime) which requires replacing at regular intervals. The advantages of an auto-zero system, in our opinion, far outweigh the disadvantages.