 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Medical component testing applications Page 2
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
4) Inhalator testing for correct spray pattern:
A major manufacturer of inhalator drug delivery systems needed to test the spray pattern at the outlet of their mouldings to ensure the spray was directed into the patient's mouth and not to one side. The existing system of testing was to select a sample component and, with a container full of ink, test spray on to a piece of card to check the pattern, a less wasteful and more convenient method was required.
We came up with the idea of incorporating two tests into one instrument, a fixture was designed that allowed a controlled pressure air supply to flow through the outlet, the hole size could be checked by measuring the air flow, also at the outlet of the jet, we sited an array of temperature sensitive micro sized thermistors, by using the self heating effect we could measure where the air flow was centred by measuring the cooling effect on the sensors, this information could then be displayed on a screen. A 10 by 10 array was adequate, this instrument was faster and had no wastage.
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
5) Multiple measurements on a medical check valve at high speed:
The same large company manufactured a check valve which had to be tested 100% for correct operation and freedom of defects.
Using our MiniFlow instrument (see page 3 of 'Leak and Flow testing') under computer control, we developed a computerised quality control instrument to measure and test these valves (non-return valves) in sequence for:
a) Low pressure air tightness,
b) Pressure at which the valve starts to open, the 'cracking' pressure,
c) The flowrate at a set higher pressure,
d) The pressure at which a set low flowrate is reached and
e) The low pressure air tightness.
The Computer had to control and measure the pressure (increasing for steps a to c and decreasing for steps c to e) and measure the airflow. The test time was 5 seconds at the end of which the computer printed out the dated test results on an adhesive label to attach to the tested valve container for complete quality control and traceability.
|
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
|
|
6) The design of a new Spirometer:
A plastics moulding company had an idea for a new spirometer design - they had the plastic moulding design expertise but they needed additional design expertise.
Most doctors' surgeries and hospitals have access to a simple but effective device to check on a patient's breathing efficiency, a spirometer, the cheapest of which consists of a plastic tube with a spring loaded movable flap. To design a new spirometer to compete even with the more expensive versions required the availability of a cheap air flow sensor, at that time all suitable sensors were much too expensive. Recently, however, a new sensor has come on the market that appears to be cost-effective and have the required accuracy with speed of response - watch this space!
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
March Designs & Measurements
Unit 11, Alfred Street
Dunstable
Beds LU5 4HZ England
|
|
|
|
|
|
|
|
|
|
|
|
|