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Regulators and Flowmeters

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  1. Regulators and Flowmeters RET 2274 Respiratory Care Theory 1 Module 3.0

  2. Regulators and Flowmeters • Regulating Gas Pressure and Flow • Cylinder gases exert too high of a pressure for use with respiratory equipment, and must be reduced to a working pressure of 50 psig (pounds per square inch gauge) • This standard pressure can be applied to power devices such as IPPB, pneumatic precursors, ventilators, etc. • Reducing valves are used to reduce high pressure to a working pressure

  3. Regulators and Flowmeters • High-Pressure Reducing Valves • Two types • Single Stage • Multiple Stage Available as preset or adjustable

  4. Regulators and Flowmeters • High-Pressure Reducing Valves • Preset Reducing Valve • Automatic adjustment of the diaphragm-spring combination keeps the pressure in the high-pressure chamber at a near-constant 50 psig; thus the name preset • Refer to Egan’s Fundamentals of Respiratory Care, Eighth Edition for a complete working description

  5. Regulators and Flowmeters • High-Pressure Reducing Valves • Preset Reducing Valve (A) High-pressure inlet (B) Pressure gauge (H) High-Pressure gas inlet (C) High-pressure chamber (I) Gas outlet (G) Valve stem (E) Flexible diaphragm (D) Ambient-pressure chamber (F) Spring

  6. Regulators and Flowmeters • High-Pressure Reducing Valves • Adjustable Reducing Valve • Some devices need variable pressures • The adjustable reducing valve allows a change in outlet pressure via a threaded hand control attached to the diaphragm • Refer to Egan’s Fundamentals of Respiratory Care, Eighth Edition for a complete working description

  7. Regulators and Flowmeters • High-Pressure Reducing Valves • Multiple-Stage Reducing Valve • Can be preset or adjustable • Reduces pressure in two or more steps • First stage – pressure is lowered to an intermediate level (200 – 700 psig) • Second stage – pressure is decreased to working level (50 psig) • Provide more precise and smooth flow control

  8. Regulators and Flowmeters • Low-Pressure Gas Flowmeters • Flowmeters are needed to set and control the rate of gas flow to a patient, either from a station outlet or a high-pressure cylinder • When using a a high-pressure cylinder as the gas source, a regulator (reducing valve plus flowmeter) is required

  9. Regulators and Flowmeters • Low-Pressure Gas Flowmeters • Three categories of flowmeters • Flow restrictor • Bourdon gage • Thorpe tube

  10. Regulators and Flowmeters • Low-Pressure Gas Flowmeters • Flow restrictor • Consists of a fixed orifice calibrated to deliver a specific flow at a constant pressure (50 psig)

  11. Regulators and Flowmeters • Low-Pressure Gas Flowmeters • Fixed Orifice Flowmeter • Provide specific flow rate settings by selecting or adjusting an outlet orifice size • This unit incorporates a reducing valve and fixed orifice flowmeter

  12. Regulators and Flowmeters • Low-Pressure Gas Flowmeters • Bourdon Gage • A flow-metering device that is always used in conjunction with an adjustable pressure reducing valve • It is a fixed orifice, variable-pressure, flow metering device

  13. Regulators and Flowmeters • Bourdon Gage • Hollow tube straightens as gas pressure increases – increasing flow through the fixed orifice • Will work in any position – ideal for transport

  14. Regulators and Flowmeters • Bourdon Gage • Not back-pressure compensated • As resistance to flow increases, the indicated flow reading becomes inaccurate

  15. Regulators and Flowmeters • Low-Pressure Gas Flowmeters • Thorpe Tube • Always attached to a 50 psig gas source – either a station outlet or a pressure reducing valve • It is a variable orifice, constant-pressure flow-metering device • Measures true flow • Refer to Egan’s Fundamentals of Respiratory Care, Eighth Edition for a complete working description

  16. Regulators and Flowmeters • Thorpe Tube • Two types • Pressure uncompensated vs. Pressure compensated

  17. Regulators and Flowmeters • Thorpe Tube • Pressure uncompensated • Uncompensated for backpressure • Needle valve is proximal to the Thorpe tube • If pressure is applied distally to the tube, e.g., kinked tubing, flow indication may be lower than delivered flow

  18. Regulators and Flowmeters • Thorpe Tube • Pressure compensated • Compensated for backpressure • Needle valve is distal to the Thorpe tube • If pressure is applied distally to the tube, e.g., flow-restricted equipment or kinked tubing, it will have NO effect on the flowmeter’s performance. The float will be an actual reading of flow delivered

  19. Regulators and Flowmeters • Ranges of Flowmeters • High-range 0 – 75 L/min (5-L/min intervals) • CPAP and high-flow oxygen delivery devices

  20. Regulators and Flowmeters • Ranges of Flowmeters • Low-range 0 – 3 L/min (1/4-L/min intervals) • Pediatric and COPD patients

  21. Regulators and Flowmeters • Ranges of Flowmeters • Standard 0 – 15 L/min (1-L/min interval) • Most oxygen delivery devices

  22. Regulators and Flowmeters • Correctly Reading a Flowmeter • Ball-float flowmeter • Read from the middle of the ball 6 L/min 2 L/min

  23. Regulators and Flowmeters • Correctly Reading a Flowmeter • Bobbin flowmeter • Read from the top of the bobbin 2 L/min

  24. Regulators and Flowmeters • Mini Clinic – Select the Proper Device Problem: An RT has an order to transport a patient to radiology with oxygen. What equipment should the therapist select? Solution: Because the RT has to transport a patient using oxygen, they should select an E cylinder with an adjustable regulator that includes a Bourdon gauge (unaffected by gravity)

  25. Regulators and Flowmeters • Mini Clinic – Select the Proper Device Problem: An RT has to set up a pneumatically powered ventilator with oxygen in the ambulatory clinic, where there are not oxygen outlets. What equipment should the therapist select? Solution: Because pneumatically powered ventilators require 50 psig and no central oxygen outlets are available, the RT needs a preset reducing valve and a large H cylinder of oxygen.

  26. Regulators and Flowmeters • Mini Clinic – Select the Proper Device Problem: An RT has to set up oxygen therapy with a jet nebulizer for a patient in the ICU. What equipment should the RT select? Solution: Because moderns ICUs have central wall outlets for oxygen, The RT needs only select a flowmeter. A compensated Thorpe tube is required for metering flow through high-resistance equipment such as jet nebulizers

  27. Regulators and Flowmeters • Attaching a Regulator to a Gas Cylinder • Select the proper gas cylinder • Ensure content of cylinder by checking the label

  28. Regulators and Flowmeters • Attaching a Regulator to a Gas Cylinder • Remove protective covering from cylinder outlet

  29. Regulators and Flowmeters • Attaching a Regulator to a Gas Cylinder • “Crack” the cylinder to remove dust, debris and moisture

  30. Regulators and Flowmeters • Attaching a Regulator to a Gas Cylinder • Select the appropriate gas regulator • Ensure that a plastic washer is in place

  31. Regulators and Flowmeters • Attaching a Regulator to a Gas Cylinder • Attach the gas regulator to the cylinder valve • It should fit into place easily - DO NOT FORCE IT!!!

  32. Regulators and Flowmeters • Attaching a Regulator to a Gas Cylinder • Tighten the fittings in place

  33. Regulators and Flowmeters • Attaching a Regulator to a Gas Cylinder • Open the cylinder valve SLOWLY and pressurize the regulator, note the amount of gas pressure in tank – listen for leaks Cylinder Wrenches

  34. Regulators and Flowmeters • Attaching a Regulator to a Gas Cylinder • Set the flowmeter to the prescribed flow rate and attach the oxygen delivery device

  35. Regulators and Flowmeters • Attaching a Regulator to a Gas Cylinder • Place the oxygen delivery device on the patient and monitor vital signs

  36. Regulators and Flowmeters • Attaching a Regulator to a Gas Cylinder • Place the oxygen delivery device on the patient and monitor vital signs