The COVOX Mixed Expired Gas Chamber however, has an internal capacity of just 500 ml, allowing much quicker sampling than standard sized chambers due to the small volume of air required to flush the chamber. The design eliminates end tidal volume bias, and being constructed of thin walled thermo-plastic, quickly assumes the temperature of exhaled air, preventing condensation within the chamber itself.

Preventive maintenance is not required. The gas sampling circuit is protected against the accumulation of expired gas moisture using a Perma Pure Nafion dryer. A reflux arrangement removes the need for regular dryer replacement.

Fully supported means just that, rental payments cover all eventualities. These include: Unlimited telephone support, replacement parts and labour, On-site support, software and hardware updates. If for any reason the equipment needs to be called in for servicing etc, we organise and cover all costs of courier collection and redelivery.


The COVOX Approach is to use simultaneously,  breath-by-breath measurement of pulmonary ventilation (where sensors are capable of high sampling rates), and a mixed expired gas chamber for Oxygen and Carbon dioxide analysis.

Industrial. At the heart of the system is an embedded  industrial PC, running under the Windows Embedded POS Ready Operating system. All the components used in the construction has a history of industrial use - reliability being of prime importance.

In the period of approximately two years since installation, COVOX has provided excellence in reliability in measurements and ease of operation. This gas analysis system has been used in approximately 7,000 exercise test analyses. It has successfully formed part of the integrated approach to teaching, research and consultancy. Ian Swaine, DEMontford University

I thought you would be interested in the present position with regard to the practical use of the COVOX Microlab in respect to non-research work within the Constabulary. All officers eligible for promotion are required to undergo a fitness assessment in order to achieve the desired level of cardiovascular performance before taking up a new post. May I take this opportunity, yet again to thank you for supplying such a suitable medium for such a demanding schedule of assessments.

David Clarke, Force Physical Education Officer, Devon and Cornwall Constabulary

I would like to thank you on behalf of West Mercia Constabulary and the NSPCC Marathon Team for the personable and professional way you conducted yourself, and the quality of the information you delivered to the group. We were all very impress by the technology (COVOX Analyser). It has given us food for thought for the future. I am sure it will go a long way to ensuring that we achieve the right result in the marathon. David Thursfield, Deputy Chief Constable, West Mercia Constabulary

I have found the COVOX to be robust, reliable and user-friendly and I can strongly recommend it for use in student laboratory work. Dr Neil Armstrong, Reader in Exercise Science, Director, P.E.A. Research Centre, University of Exeter

I have been using the COVOX Gas Analysis System since 1988 in Leisure Centres in Teignmouth and Torbay. It provides an accurate measurement of oxygen consumption, which is reliable and repeatable. I have been very satisfied with the apparatus and with the results that it provides.

Dr P.R. Travers, M.B.,B.S., D.Phys. Med

I am pleased to report many years of excellent performance from our COVOX System. We have only two problems at the moment : 1) Can you send us a replacement dryrite container. A student dropped the original. 2) The software occasionally crashes, usually at the point of printing out the results, I think because the datafiles are almost full. How do we fix this problem? I would be interested in your comments on the longevity of our COVOX and if you think upgrades are possible. Please send a current brochure.  Dr Martin Farrally, St Andrews University.

A rugged respiratory gas analyser, ideally suited to busy teaching laboratories. All the usual cardiovascular response to exercise measurements are reported.

Quick and simple calibration provides excellent repeatability.

Click here to request more information

Over the years we’ve worked with many clients, each having one thing in common – the wish to provide scientifically accredited aerobic measurements – without breaking the budget.

We don’t claim that our metabolic cart is better than all others. We believe however, that our innovative bespoke manufacturing approach, provides a cost competitive alternative to respiratory gas analysers found in today’s market place.

Our current ‘ruggedised’ analyser is designed to be used in busy teaching laboratories, where students’ can get hands on experience with an on-line system, with little risk of causing expensive accidental damage.



Purchase Cost


Metabolic Cart



Power Supply



Breathing Tube x 2



Calibration Syringe



Breathing Valve



Valve Adapter



Small Adult Face Mask



Medium Adult Face Mask



Large Adult Face Mask



Head Strap


Full Purchase Price

£9220 please see itemisation below.

Rent This Analyser

Complete system including full maintenance and fully supported:

Initial monthly rental £300 subject to a minimum rental of 4 months reducing to £95 per month thereafter. Return at any time without penalty.

Size 36w, 30d, 15h cm

Constructed using tried and tested industrial components, this is a ‘work horse’ analyser capable of continuous use - without the need for preventive maintenance.


Mixed Expired Gas Analysis

Our decision to use a mixing chamber instead of Breath-by-breath gas analysis is based on the ever decreasing time (often less than 500ms), that is available for analysing each breath directly. Timing has implications concerning repeatability, where sampling conditions should remain as constant as possible.

To avoid end tidal volume bias, standard size mixing chambers have volumes usually between 5 -7 litres. This can limit the sensitivity to rapid changes in metabolism due to the relatively large volume of air required to flush the chamber. The accumulation of moisture can also cause problems. Nevertheless mixing chambers enable reliable and repeatable expired gas analyses. See Redbackbiotek for their Mixing Chamber Vs Breath by Breath article.

The COVOX Metabolic Cart detects instantaneous inspired respiratory air during each breath using a Fleisch pneumotachograph, which due to its excellent linearity and turn down ratio, allows accurate measurement of pulmonary ventilation (Ve) from rest to VO2max, using a single flow head.

The advantages of Fleisch diagnostic flow measuring systems include: Accurate and linear measurements throughout the flow range, robustness and no moving parts. Pneumotach moisture contamination is avoided by measuring inspired respiratory air, thereby eliminating surface condensation and contamination from moisture in the breath. An ultra low resistance filter is used to capture dust particles, further protecting the flow head.


Typically +/- 1.5%

Min Flow 0.02 l/s

Max Flow 16 l/s

Linearity +/- 1%


Quick and simple and takes less than a minute. A single stroke from a 3-litre calibration syringe is all that is required

This differential pressure, which is measured by a pressure sensor (2), is directly proportional to the flow rate. The output from the pressure sensor is passed through an A-D converter, the signals from which are used to give calibrated flow and volume measurements.

Inside the flowhead (1) is a bundle of capillary tubes that create a pattern of laminar air flow, and introduces a very slight resistance to the flow of air causing a differential pressure.

Airflow Measurement

COVOX uses the Teledyne UFO oxygen sensor, which was specifically developed as a reliable alternative to paramagnetic and optical sensors. The Teledyne UFO utilises fuel cell technology that is inherently rugged and forgiving.

Unlike many other sensors the UFO is insensitive to shock, vibration and will withstand exposure to moisture without damage. With an average response time of 100 milliseconds, the UFO is one of the fastest oxygen sensors in general use.

The sensor meets ISO 7767 (1997), ASTM F1462-93, and CE Medical Devices Directives.

Accuracy better than +/- 1.0% Reading

Resolution 0.1%

Oxygen Sensor

Question: Why does COVOX use a pneumotach rather than a turbine to measure pulmonary ventilation?

Answer: In a word – reliability. Turbines are mechanical devices prone to damage in a busy laboratory environment. Pneumotachs are effectively solid state – no moving parts to wear out or go wrong!

Question: Moisture can affect pneumotachs. How do you overcome the pneumotach from being contaminated with moist breath?

Answer: Simple, we measure pulmonary ventilation on inspiration. The pneumotach only comes into contact with room air.

Question: How does the pneumotach deal with temperature change?

Answer: Temperature change results in a change in air viscosity, which can affect pneumotachs. COVOX software however allows you to calibrate the pneumotach quickly to suit the environmental conditions, in less than a minute.

Question: Is it possible to check the accuracy of the pneumotach measurement?

Answer: Yes. Volume can be checked using a calibration syringe. In addition system software contains a routine that allows you to measure actual flow rate throughout the range.

Question: Why does COVOX use a mixing chamber rather than breath by breath analysis?

Answer: Mixing chambers provide significantly better repeatability.

Question: How is moisture prevented from building up in the mixing chamber?

Answer: The mixing chamber is constructed of thin but strong thermoplastic material. During a test the chamber walls quickly assume the temperature of the expired air, thereby preventing condensation.

Question: What is meant by integrated analyser?

Answer: All instrumentation, including embedded PC is contained within a strong but portable enclosure, which provides excellent protection.

Question: How durable are the breathing tubes?

Answer: The breathing tubes are made from ultra light falconia tubing, used in the aircraft industry. These tubes are virtually indestructible in normal use.

Question: The response from traditional mixing chambers is usually much slower than breath by breath analysis, therefore is COVOX suitable for VO2max testing?

Answer: Yes it is! The COVOX mixing chamber has a very small mixing volume, but at the same time avoids end tidal volume bias. This results in a quick response time. Furthermore the mixing chamber is sampled after each breath, and if used in predictive mode, constantly updates minute values as the test progresses.

Breathing Circuit

The exercise non re-breathing valve allows air to be inhaled through the pneumotach and then vented through a mixing chamber where the expired gas is presented for analysis.

Recurring Gas Sampling Minute Sequence

Gas Sampling phase 1: Room air is drawn through the gas sampling circuit and analysed for ambient (ie. inspired) oxygen and carbon dioxide  concentration (FiO2) and (FiCO2). This period can be set between 10 and 25 seconds. Note that during this phase expired gas continues to be mixed and the chamber ‘updated’, but not reported.

Gas Sampling phase 2: Expired gas is drawn from the mixing chamber for analysis. VO2 is updated and displayed after each breath.

Predictive Sampling Option

When selected this option predicts minute VO2 after each breath. The prediction improves as the minute sampling interval progresses.


All prices exclude VAT

About COVOX : Reviews  :  Contact : Video

A Robust Laboratory Respiratory Gas Analyser

 Short & Indefinite Term Rental


COVOX Metabolic Cart   Why Buy When You Can Rent? % CO2 Eliminated %CO2 CO2 Production in Litres / min VCO2 Ventilatory equivalent for CO2 VcO Response to Exercise Measurements Standard Measurements Optional Measurements

Pulmonary Ventilation Percentage of Oxygen Absorbed Oxygen Consumption in L/min Oxygen Consumption / Body Wt Ve %O2 VO2 VO2bw Respiration Rate RR Respiratory Exchange Ratio RER Ventilatory equivalent for Oxygen VeO Tidal Volume Tv

Please contact us for more information

07977 491979

01392 201956

Rugged - all the components are enclosed within an aluminium case. This offers excellent protection and reduces the possibility of accidental damage to expensive sensors