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Breathing Simulators

Si-Plan Electronics Research Ltd manufactures breathing simulators in two sizes:
The '300' Breathing Simulator The '625' Breathing Simulator
Maximum tidal volume of 3 litres Maximum tidal volume of 6.25 litres
Illustrated with case removed Illustrated with case removed

Complete Breathing Simulator
enclosed in case

The current breathing simulator technology is available in two sizes: the '625' has a maximum tidal volume of 6.25 litres and the '300' has a maximum tidal volume of 3 litres.

Each breathing simulator is a self-contained unit controlled and monitored by the RS232 serial port of a PC.

  • Electrical supply required: 110/230 volts AC.
  • Compressed air supply required: between 5 and 10 bar.
    (The figures quoted below in 'System Description and Specification' are based on an air supply pressure of 6 bar.)

The Breathing Simulator is also available in a version with remote power supply and control systems for special applications, for example oxygen-rich atmospheres.

  • Maximum voltage in the special-version breathing simulator: 24 volts DC.
  • Compressed air supply required: between 5 and 10 bar.
    (The figures quoted below in 'System Description and Specification' are based on an air supply pressure of 6 bar.)

The serial link with the PC enables the user to:

  • load breathing waveforms;
  • view flow profiles generated by the operation of the simulator;
  • initiate start and stop;
  • record data in CSV format.

Modes of use

  • Running as an independent unit
    • to simulate a pilot, fire-fighter or diver to evaluate breathing support systems;
    • to simulate patient breathing profiles (for medical and pharmaceutical applications).
  • Two breathing simulators can be run independently with phased or beating waveforms to simulate two breathers being sustained by one breathing support system.
  • Two breathing simulators can be run with phased waveforms to evaluate a breathing support system in conjunction with g-suit pressure system, eg pilot.
  • Two sets of two breathing simulators can be run in a linked mode to simulate two breathers with g-suits breathing on the same life support system.

System Description and Specification

The Breathing Simulator system consists of a stainless steel bellows driven by a servo-pneumatic system. The servo pneumatic system comprises an ultra low-friction, purpose builtpneumatic actuators with integral displacement/velocity transducer (analogous to volume and flow) and manifold-mounted servo valve. The servo control loop works in displacement control and is implemented on a dedicated RISC processor, which also stores flow breathing profiles. The RISC processor performs the necessary mathematical integration to convert the flow profiles into balanced volume waveforms, implementing the servo-control algorithm.

The system features a built-in air on-off valve which enables an automatic shutdown after a preset period to conserve the air supply. A clean, dry air supply is required which may be from bottled air or from a compressor.

Breathing Simulator System Specification
Characteristic'300' Simulator'625' Simulator
Maximum tidal volume3 litres6.25 litres
Minimum tidal volume50 millilitres100 millilitres
Minimum breaths per minute55
Maximum breaths per minute10060
Maximum minute volume180 litres per minute375 litres per minute
Minimum minute volume0.25 litres per minute0.5 litres per minute
Maximum flow:
...step input to bellows position1000 litres/minute1200 litres per minute
...sinusoidal wave at 1 hertz500 litres/minute800 litres per minute
...square wave at 1 hertz500 litres/minute800 litres per minute
Maximum rate of change of flow (gas acceleration)*Up to 600 l/sec2**Up to 444 l/sec2
Normal working pressure of bellowsUp to 10 kPa.gUp to 10 kPa.g
Maximum differential bellows pressure40 kPa.g40 kPa.g
Height (including feet and handles)410 mm410 mm
Width355 mm355 mm
Depth355 mm355 mm
Weight40 kg40 kg

*0 to 800 l/min in 20 milliseconds.
**0 to 800 l/min in 30 milliseconds.
Figures quoted above are based on an air supply pressure of 6 bar.

Operating conditions

The Breathing Simulator bellow assemblies are designed to operate under the following conditions

  • Ambient pressure range 2 to 1200 mbar (abs);
  • Ambient temperature range: minus 5 to plus 50 degrees centigrade;
  • Ambient humidity range up to 90% relative humidity.

Software package

The software package was originally written to run on an Acorn RISC PC. It has been re-written to operate on Windows 95 and Windows NT.

The computer operating system enables:
  • Breathing profiles to be loaded in CSV format
  • Downloading and storage of breathing profiles in the RISC processor within the breathing simulator.
  • Setting of parameters for each breathing machine:
    • select breath profiles;
    • set breathing rate; } set any 2 parameters
    • set tidal volume; } the third is calculated
    • set minute volume; } and the value displayed.
    • set number of cycles.
    • set phase angle (in linked simulators);
  • Viewing of flow profiles generated by the operation of the simulator;
  • Start and stop control;
  • Recording data in CSV format.
  • Control of up to four (linked) breathing machines.
  • Graphic dynamic display of bellows position.
  • Static display of actual volume/flow waveform (refreshed periodically).

Optional software packages

  • Profile generation software enables breathing profiles to be viewed, created, edited and exported for loading into the simulator control software. CSV files can be imported for editing.
  • Sequencing software allows a sequence of varying profiles to be strung together to recreate the changes in breathing patterns of a subject in a real-life situation. The sequence is executed automatically by the software program. Sequences can be saved, recalled at a later date, copied and edited.

Generation of breathing profiles

This can be:

  • customer defined/supplied in CSV format;
  • written or generated in the optional profile generation software described above (in CSV format);
  • recorded from living subjects by optional Si-Plan pneumatach system.

PC requirements

Suggested specification:
  • 1 x Intel Pentium III 450 MHz PC running Windows NT;
  • 3.5" floppy disc drive;
  • 32Mb SDRAM (minimum);
  • Video card: 8Mb video ram;
  • 24 speed CDROM drive;
  • 11.5 gigabyte UDMA hard disc drive;
  • 17" colour monitor (1280 x 1024);
  • Keyboard and mouse;

  • Ethernet Card;
  • Data backup, for example:
    • ZIP Drive: 100 megabyte;
    • Travan tape: 8 gigabyte;
    • Rewritable CD 640 megabyte.

Si-Plan is able to quote for the supply of a suitable computer.

All prices are available on application.

Updated 20 April 2005

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Si-Plan Electronics Research Ltd, Avenue Farm Industrial Estate,
Birmingham Road, Stratford-upon-Avon, CV37 0HR, UK
Tel International: +44 1789 205849 | Tel UK: 01789 205849
Fax International: +44 1789 415550 | Fax UK: 01789 415550

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