Frequently asked questions


If you have the older machiens which which use an internal PCI DAQ card click here.

Pre-sales questions

What method of sealing is the piston to cylinder interface?
Where can we source spare cylinder seals, should they become necessary?
What is the maximum pressure differential between the two sides of the piston?
What is the maximum operational pressure of the machine?
What is the range of flows/tidal volumes?
What LabVIEW software versions are available?
Is the source code available?
What sort of warranty is supplied with the machines?
How would delivery be achieved?
What is the likely delivery schedule?
What size air fittings are supplied?

Set-up questions

What is the correct USB configuration?

Support questions

Opening the machine

Flow measurement unit

What are the connections to the breathing measurement unit and how does it work?

Pre sales questions

What method of sealing is the piston to cylinder interface?
Sealing of the piston around the cylinder wall is achieved in the earlier machines by the use of a labyrinth seal. This means that there is no wear component in the system, but equally means that there can be cross contamination between the two sides of the piston and a pressure differential across it cannot be maintained.
Later versions of the machine (post July 2009) use a wiper seal at the periphery of the piston to remove these limitations but this does introduce a wear component that may need replacing very occasionally (depending upon the usage of the machine).

Where can we source spare cylinder seals, should they become necessary?
Spare cylinder seals are available directly from Warwick Technology Limited.

What is the maximum pressure differential between the two sides of the piston?
The machine is designed to operate with the two sides of the piston almost pressure balanced. The pressure top and bottom can vary by approximately breathing pressure differentials - i.e. up to 200mBar.

What is the maximum operational pressure of the machine?
The basic machine has been built to operate at atmospheric pressures. However, a version has been developed for use with hyperbaric breathing chambers, operating at up to 61 bar (proof pressure 100 bar). Other requirements can be designed and constructed as required.

What is the range of flows/tidal volumes?
As the system is electronically controlled, the flow rates and/or tidal volumes are infinitely variable up to the maximums quoted. See elsewhere on this website for the standard machines properties. At the very low flow rates/tidal volumes (>2%max) the machines may be less accurate in generating the waveform as the piston will not be moving a great deal and compressibility becomes more of a factor. Machines with different (small or larger) limitations can be easily developed to order.

What LabVIEW software versions are available?
The LabVIEW software provided with the machines is currently to LabVIEW version 8.6. Later versions of LabVIEW will automatically convert older versions when loaded.

Is the source code available?
The machines are provided with the full code versions of the LabVIEW VIs i.e. with the source code attached. This enables users to develop or customise the software further if required. The code is provided locked against accidental modification but not password protected.

What sort of warranty is supplied with the machines?
The machines are warranted against defects in material or manufacture for a period of one year from date of delivery. Repair and service will be undertaken by either Warwick Technology ourselves or directly by the major component suppliers.

How would delivery be achieved?
Delivery within the UK will usually be undertaken personally by Warwick Technology Limited. Delivery to clients abroad is undertaken using air freight shipping. The machine is supplied in one wooden crate (415x415x700mm - 75kg) containing the machine itself and all it's associated equipment.

What is the likely delivery schedule?
All machines are built to order and manufacture is normally expected to take 10-12 weeks from receipt of order. Non-standard machines may take a couple of weeks longer. Air freight shipping to overseas customer can add 7-10days. Contact us for more information.

What size air fittings are supplied?
As standard the machine is fitted with two 1"BSP stainless steel hose tails on elbows, one screwed into each of the top and bottom plates. Different configurations of fittings and locations are available as required.

Set-up questions

What is the correct USB configuration?
The ssoftware has been writtena ssuming the USb unit will be cofigured as 'DEV1' in Measurement and Automation Explorer (MAX). If this is not set correctly the software will not operate correctly, if at all.

The USB configuration can be accessed and altered using the Measurement and Automation Explorer (MAX) installed with the DAQ card drivers. Refer to the National Instruments manual for details..

Support questions

This section is being rewritten for the new Xenus controller and and will be updated shortly.

Opening the machine
Should you need to open the machine then it is important to contact us for detailed instructions. Opening or dismantling the machine should only be attempted under our instructions. Failure to abide by this request may invalidate the warranty.

Flow measurement unit

What are the connections to the breathing measurement unit and how does it work?
The breathing measurement unit consists of a flow head, within which the air passes through a gauze, and a digital manometer, which measures to pressure drop across the gauze created by the airflow, and converts this to a flow rate. The flow rate value is provided as a voltage at the connection at the back of the unit and a lead is provided to plug into the interface box on the machine. The voltage conversion on the standard measurement unit is 5vdc for 1000LPM. It does not matter which way around the two pressure pipes are connected to flow head. Reversing them just reverses the positive measurement direction of the flow .











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