Hydrophobic Filters

Firstly a few notes on oil less piston vacuum pumps
• Oil less piston pumping provides a clean vacuum without oil vapour.
• Large air flow rate and higher vacuum.
• Lower power consumption since lower HP motor is sufficient.
• Quieter operation compared to oil ring pumps since it is not scraping / rubbing of vanes to produce vacuum
• Self‐cooling air draft system effectively lower the motor temperature.
• Piston rings are made of special wear‐resistant Teflon material
• Hardness and wear‐resistant of cylinders are made of Teflon.
• Aluminium alloy exterior inside lining fully Teflon.
• Robust and long lifetime since Teflon is self‐lubricating.
• Maintenance free since no top up oil or replacement of clogged oil is required. No motor burnouts.

GENERAL WARNINGS FOR ANY PISTON VACUUM PUMPS
• DO NOT USE PUMP FOR SMOKE EVACUATION, IT WILL CLOG PUMP HEAD OVER A SHORT
PERIOD AND DAMAGE THE PUMP BEYOND REPAIR.THE SURGICAL SMOKE CONTAINS BLOOD
PARTICLES WHICH ARE STICKY.
• DO NOT USE THIS PUMP WITHOUT PROPER HYDROPHOBIC FILTER, WARRANTY WILL BE VOID
• REPLACE FILTER WHEN FILTER COLOUR CHANGES.

The most common reason for vacuum pump failure in aspiration applications is the entry of liquid vapour into the pump mechanism. Liquids ingested into the pump mechanism will lead to the valves failing or a diaphragm rupturing.

Primary protection is provided by float assembly in the collection bottles. The hydrophobic inline filter further protects the pump from aerosol (not just liquid, but vapour also) ingestion.

In general oil ring pumps, there is oil inside which is the lubricating medium. Hence the vacuum and flow rate will be lover in addition to unclean suction. Oil type suction pumps wear out much faster and consume more power.

In these normal oil type pumps, even if no filter is use, the liquid / blood etc. goes into the pump and leads to much faster failure of the pump as the oil a mixed with the liquids sucked in and jams up.

What is the basic difference between piston vacuum pump and oil ring vacuum pump? 

Oil ring vacuum pumps have a rotating vane (blade) system that moves inside a circular chamber to produce vacuum. These vanes suck out air to produce vacuum. The continuous rubbing of the metal vanes to produce vacuum results in faster wear and tear. The oil medium is instead for lubrication and retention of vacuum.
During use in OT, oil gets mixed with surgical fluid vapour and becomes thicker and sticky. This results in faster wear out of rotating vanes. Consequently the vacuum falls from 700 mm Hg to 400 mm Hg within one year. The oil stickiness gets very tough in some cases and motor burn out occurs. Even if motor is rewound or replaced and also oil is replaced the vanes wear out is not preventable. Past one year the vanes wear out increase further and vacuum may fall to 300
or 100 mm Hg. Then the customer orders another pump set.

Another important point is that flow rate (speed of pumping) is only 15 to 20 litres maximumfor oil ring vacuum pumps.

For oil less piston vacuum pumps the piston and cylinder have Teflon linings. Teflon is selflubricating and hence oil is required. The sealing is so perfect with the piston system that vacuum builds up very fast. The flow rate (speed of pump) attainable is 40 to 50 litres per minute. The vacuum holds a steady 600 to 700mm Hg for a long time.

But if surgical fluid vapour which contains blood particles is allowed to enter the piston & cylinder assembly then it gets sticky inside. Being a sealed monoblock pump no further repair are possible. Hence protective hydrophobic filters are provided to prevent the entry of all kinds of liquid vapour. These filters are to replaced periodically as and when the filter colour changes from pure white to yellow or light brown.

The life time of piston vacuum pumps is 5 to 6 years compared with 1 to 1 ½ years for oil pumps. If used with care piston pumps can last up to 10 years.