Over the past ten years Blease Medical has fitted more that 20,000 Burkert proportional flow valves in its range of operating theatre ventilators, without a single field failure
Blease Medical produces a range of anaesthetic ventilators to care for patients in the operating theatre.
The machines are designed to deliver a carefully regulated mixture of oxygen, nitrous oxide and an anaesthetic agent gas to keep patients asleep and pain free during surgery.
They also act as life support systems by 'breathing' for patients who need deep anaesthesia when undergoing seriously invasive surgery. Explains Blease Medical technical director Richard Cooke: "In hospital emergency departments such as those seen in TV programmes like ER or Casualty, nurses and doctors are often seen squeezing a bag to ventilate patients.
"Our machines automate this process for the operating theatre where patients may need to be ventilated for hours".
The mechanism that automatically squeezes the bag is contained inside a plastic dome.
The outside of the bag is pressurised within the dome using oxygen and air, which provides the 'squeezing' action to deliver the precise amount of anaesthetic gas to the patient's lungs.
Sensors and transducers measure the exact volume of gas used to squeeze the bag.
Obviously, delivering the volume of gas required to squeeze the bag is critical to the operation of the system, which is why Cooke specifies Burkert oxygen-safe proportional flow valves.
Commenting on the reason's for choosing Burkert equipment, Cooke says: "Finding the right proportional flow valve was not easy and in the early stages of the ventilator design we even tested a US valve that was used primarily in helicopters and jet engines. "But while it met the specification, it proved to be too expensive for this application".
After contacting Burkert, Cooke first tested one of the company's 4mm orifice valves that wasn't quite able to provide the detail needed in the low end of the range of control.
Burkert's local sales engineer then suggested two 1.6mm valves in parallel, a configuration that achieved the required performance and avoided the need to design a special valve.
Cooke says the design-in process was also painless.
"I am an electronics design engineer and therefore had to cope with a learning curve in pneumatics, so I appreciated the help from Burkert in the UK. "Some calculations were also done by engineers in Germany to prove that what we were planning was viable".
Summing up, Cooke says Blease Medical has every reason to be happy with Burkert's performance: "We manufacture over 1000 machines per annum and use two Burkert valves per machine, and we have done since the early nineties.
"In all that time, with over 20,000 valves fitted, we've never had a field failure. "And where patients' lives are at stake, that level of reliability is not only reassuring - it's vital."
