The PULSI 200LR system comprises four standard units: the PULSI 200LR OPTICAL HEAD UNIT (OHU), the ANALYSER CONTROL UNIT (ACU), and the AUTOZERO UNIT (AZU).
An IN-SITU HEATER (ISH) is optionally supplied when process conditions are liable to result in water condensing in the analyser. The instrument operates on the dual wavelength infra-red principle where pulses of two wavelengths, per gas, at specific wavelengths, are sent through the sample cell of the STACK MOUNTED OPTICAL HEAD UNIT (OHU).
The ‘measure’ pulse is partially absorbed by the gaseous component(s) to be measured whilst the ‘reference’ PULSI is relatively unaffected. A total of 8 wavelengths are available and in some circumstances reference wavelengths are shared. This allows up to six (6) gas phase concentrations to be measured simultaneously.
The specific wavelengths used for analysis are application dependent and selected by the Procal Analytics Application Group before each instrument is calibrated. The selected infra-red wavelengths (8) used for analysis are obtained by means of interference filters and gas filled cells (GFC) mounted on a rotating wheel located in the STACK MOUNTED OPTICAL HEAD UNIT.
The PULSI 200LR Series has resulted from the culmination of many years research and development into stack gas analysis. The advanced stack gas analyser utilises an in situ (inside the stack) sample cell thereby avoiding the need to extract a sample from the stack.
This avoids the use of costly, high maintenance sample handling systems, but more importantly analyses an UNMODIFIED, truly representative gas sample. Sintered stainless steel filter panels fitted to the sides of the in-stack measuring cell allow the permeation of stack gas whilst preventing the ingress of dust and particulates.
The envelope thus formed allows the introduction of zero and span gases. The OPTICAL HEAD UNIT requires no independent power supply; all necessary power is supplied via the ACU interconnection cable. The ANALYSER CONTROL UNIT (ACU) displays gas concentrations on the integral liquid crystal display along with information on sample conditions, diagnostic data and trends.
The information can be retransmitted in the form of 4-20mA current outputs (one per measured component), parallel printer interface and optional RS232C serial output. The OHU controls the AUTOZERO UNIT. On command from the ANALYSER CONTROL UNIT, the AZU will initiate a zero check on the system by filling the sample probe with zero gas typically clean, dry instrument air.
In addition to the auto zero function, the AZU has a safety feature which, in the event of power loss to the analyser, or too low a sample temperature will purge the sample cell with instrument air. This is done to prevent highly corrosive condensates forming in the sample cell.
The OHU also controls the temperature of the optional IN-SITU HEATER which is used if the analyser is required to operate in stacks or ducts where the sample gas temperature is below its dew point. In this application the ISH requires a mains supply.