Reduc vals, reguls  flowmtrs bb 10.11
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Reduc vals, reguls flowmtrs bb 10.11

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purpsoe, function and application

purpsoe, function and application

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  • Different connections, density of gases

Reduc vals, reguls  flowmtrs bb 10.11 Reduc vals, reguls flowmtrs bb 10.11 Presentation Transcript

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