Purpose: A suction/pressure unit can provide controlled pressure, vacuum, or both. They can be portable or fixed Suction Units Uses

High volume • Saliva evacuators in dental • Surgery and ER for drainage of wounds and massive

bleeding • On "crash carts" for quick aspiration during emergencies

SUCTION UNITS

Low volume ENT-for minor surgery, ear irrigation, etc Wards-thermatic units for slow drainage Various lab and dental equipment; cell counters, vacuum

mixer investor, porcelain furnace Pressure Units Uses

Automatic BP cuffs Nebulizers and portable ventilators Impedance audiometers and tympanographs Automated lab equipment to operate valves, pistons,

etc

SUCTION UNITS

Types of Suction/Pressure Units Piston

Operates on principle of moving piston inside a cylinder

Valves (either cam operated or reed) control direction of air flow

Vary greatly in size Can achieve extremely high volume and pressures Usually require maintenance of oil level-although

some are "oil less"

SUCTION UNITS

Oscillating pumps A rapidly oscillating rubber diaphragm replaces the

moving piston Small versions (aquarium pump style) are found in

some cell counters Larger versions are seen in dental lab Can obtain fairly good vacuum and pressure Virtually maintenance free Does require periodic

replacement of diaphragm

SUCTION UNITS

Rotary vane Uses an eccentric rotor within a cylinder

Movable vanes keep tight seal Air intake provides vacuum Exhaust side supplies pressure  

Can obtain very high vacuum Very common throughout hospital (portable

pressure/suction units) Require periodic maintenance of oil level and

cleaning of vanes

SUCTION UNITS

Thermotic (Intermittent) Uses principle of Charles's Law

Gas expands when heated The gas contracts when cooled  

Valves control direction of air flow Used for vacuum applications only Vacuum produced is cyclic-intermittent Extremely low vacuum and volume No moving parts and maintenance free

SUCTION UNITS

Measurement Vacuum

mmHg (millimeters of Mercury) inches of Hg (Hg = Mercury) cm of Hg (cm = centimeters) inches of water cm of water

SUCTION UNITS

Pressure • lb/sq in (pounds per square inch) • Kg/sq cm (kilograms per square centimeter) • mmHg • inches of Hg

Flow rate • cu ft/min • liters/min • liters/hr

Conversions - units of measurements within each category can be converted

SUCTION UNITS