Reduc vals, reguls flowmtrs bb 10.11


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  • Different connections, density of gases
  • Reduc vals, reguls flowmtrs bb 10.11

    2. 2. DEFINITIONS <ul><li>Reducing valve – a valve that reduces a higher pressure to a lower pressure </li></ul><ul><li>Flowmeter- a device that controls & indicates flow </li></ul><ul><li>Regulator – a reducing valve & a flowmeter </li></ul>
    3. 3. Reducing Valves? What’s important? <ul><li>These types of valves decrease high pressures - 2200 psi to working pressure - 50 psi for most respiratory therapy equipment </li></ul><ul><li>Also used to decrease the bulk storage pressure to 50 psi </li></ul>
    4. 4. Reducing valves (regulators) Classification <ul><li>Single-stage regulator- two opposing forces (spring tension and gas pressure) are separated by a thin diaphragm </li></ul><ul><ul><li>The diaphragm is straight & the inlet valve is closed when the forces are equal </li></ul></ul><ul><ul><li>The spring tension (for resp. set @ 50 psi but may be adjustable) should be equal to the gas pressure, but when the gas pressure drops, the inlet opens and gas enters and equilibrates to the spring tension </li></ul></ul>
    5. 5. Multi-stage Regulators <ul><li>Utilizes two or more single stage regulators in a series </li></ul><ul><ul><li>Double stage – 2200 psi to 700 psi to 50 psi </li></ul></ul><ul><ul><li>Triple – 2200 psi to 700 psi to 300 psi to 50 psi </li></ul></ul><ul><ul><li>Multistage are more precise and have more “laminar” flow </li></ul></ul><ul><ul><li>EACH STAGE MUST HAVE A POP-OFF VALVE TO RELEASE EXCESS PRESSURE </li></ul></ul><ul><ul><li>COUNT THE POP-OFFS TO IDENTIFY THE # OF STAGES </li></ul></ul>
    6. 6. Preset Reducing Valve <ul><li>A Gas inlet </li></ul><ul><li>B Gauge </li></ul><ul><li>C High pressure chamber </li></ul><ul><li>D Low pressure chamber </li></ul><ul><li>E Diaphragm </li></ul><ul><li>F Spring </li></ul><ul><li>G Valve stem </li></ul><ul><li>H Inlet valve </li></ul><ul><li>I Gas outlet </li></ul><ul><li>L Safety vent </li></ul>
    7. 7. Adjustable Reducing Valve
    8. 8. Bourdon Gauge
    9. 9. It’s a Bourdon Gauge!! But how does it work? <ul><li>Basically, pressure enters a chamber that has a fixed orifice outlet. As the pressure is increased, the coiled copper tube straightens out and the needle valve turns to read a higher unit. </li></ul><ul><li>Bourdon gauges can be calibrated to read pressure – Bourdon regulator </li></ul><ul><li>Or a Bourdon gauge can be calibrated to flow - a Bourdon flowmeter </li></ul>
    10. 10. Bourdon Gauge
    11. 11. Bourdon spring
    12. 12. Thorpe tubes
    13. 13. Thorpe-Tube Flowmeters 2 Types <ul><li>1. Non-back pressure compensated thorpe-tube flowmeter </li></ul><ul><ul><li>The needle valve is before the tube indicator </li></ul></ul><ul><ul><li>The thorpe-tube is not pressurized to 50 psi </li></ul></ul><ul><ul><li>Back pressure will cause the float to drop and the patient will receive more flow than the tube indicates </li></ul></ul>
    14. 14. Thorpe-tube flowmeters Compensated <ul><li>2. Pressure-compensated Thorpe-tube flowmeter </li></ul><ul><ul><li>Needle-valve (flow control) located distal to the Thorpe-tube </li></ul></ul><ul><ul><li>Pressure in tube is pressurized to 50 psi </li></ul></ul><ul><ul><li>If resistance is placed downstream from the Thorpe-tube the flow will read accurate </li></ul></ul>
    15. 15. <ul><li>Uncompensated </li></ul><ul><li>Compensated </li></ul>
    16. 16. How to tell the difference? <ul><li>1. The label </li></ul><ul><li>2. “Test” With the needle valve turned off, place the flowmeter in a 50 psi gas source, if pressure-compensated, the float will jump up and fall back to zero </li></ul><ul><li>Location of the needle valve ? </li></ul><ul><li>Occlude outlet and read flow? </li></ul>
    17. 17. FLOW RANGE FOR FLOWMETERS <ul><li>Usually a flowmeter is incremented up to 15 L /min </li></ul><ul><li>This varies- </li></ul><ul><ul><li>Neonate – mL/min </li></ul></ul><ul><ul><li>Incremented up to 3 L/min </li></ul></ul><ul><ul><li>Pediatrics up to 8 L/min </li></ul></ul><ul><ul><li>Some adult flowmeters go up to 25 L/min </li></ul></ul>
    18. 18. BOURDON FLOWMETER <ul><li>A reducing valve that controls the pressure gradient thru a fixed orifice </li></ul><ul><li>As the driving pressure increases the flow exiting the orifice increases </li></ul><ul><li>NOT-pressure compensated </li></ul><ul><li>If back pressure is placed downstream, the meter will read higher than what is exiting the orifice </li></ul>
    19. 19. regulators <ul><li>1. Thorpe-tube type- has to stay vertical </li></ul><ul><li>2. Bourdon type- good for transports </li></ul>
    20. 20. FLOW RESTRICTORS – functions like a Bourdon <ul><li>Type 1 –Fixed-orifice </li></ul><ul><li>Type II – Adjustable-orifice </li></ul>