821S Gas Divider

The Signal Group’s 821S Gas Divider enables the users of gas analysers to test the linearity of their instruments – simply, quickly and accurately. The 821S has ten identical capillaries and a precision balance regulator. The span gas can be selected to flow through a number of those capillaries with the diluent flowing through the remainder, to produce a ratio.

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Key Features

• Extremely reliable repeatability performance of +/-0.5% of point

• Simple to operate

• Remote control allowing automated instrument linearity auditing and calibration

• UKAS and NIST calibration available

• Remote control audit software available

• Ideal for regulated gas analyzer auditing and calibration e.g. QAL2 US EPA CFR40 Part 1065

• Compliant with international standards


➔ Datasheet

➔ User Manual

➔ Ancillary Equipment Brochure


Agricultural emissions monitoring



Biological process monitoring

Biomass combustion monitoring

Boiler and Combustion Performance

Boiler/stove emissions compliance


Carbon capture and storage (CCS)

Catalyst Research

Combustion efficiency

Combustion emissions monitoring

Combustion research

Compliance monitoring

Container leakage control/monitoring

Continuous emissions monitoring (CEM)

Controlled atmosphere storage

Direct Reduction Iron (DRI) process emission monitoring

Engine Exhaust

Ethylene production

Fermentation monitoring

Flue gas emissions monitoring

Fuel cell analysis

Gas purity

Gas turbine exhaust emissions

Linearity Checking


Modified atmosphere packaging (MAP)

NOx converter efficiency testing

NOx emissions monitoring

Process control

Process Emission Monitoring

Scrubber efficiency

Source emissions

Toxic Gas Measurement

Vehicle emissions

Technical Specification

DILUTION STEPS: 0, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% concentration of gas to be diluted.


UNCERTAINTY:  Within 0.5% of selected step.

OUTPUT GAS FLOWRATE:  1 litre/minute to 5 litres/minute.

INPUT GAS PRESSURES: zero gas: 2.5 bar, span gas: 2 bar.

CORROSION RESISTANCE:  all wetted parts are 316 stainless steel or Nitrile.

PRESSURE BALANCE: electronic transducer with front panel gauge displaying pressure balance.

REMOTE CONTROL: optional RS232 interface.

REMOTE CONTROL SOFTWARE: optional software suite to allow fully automated test and relinearization of Signal series 4 analysers.

POWER REQUIREMENTS:  220-250V AC or 110-120V AC.