Regulators and Flowmeters

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Regulators and Flowmeters

• RET 2274
• Respiratory Care Theory 1
• Module 3.0

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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

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Regulators and Flowmeters

• High-Pressure Reducing Valves
• Two types
• Single Stage
• Multiple Stage
• Available as preset or adjustable

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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 Egans Fundamentals of Respiratory Care,
  Eighth Edition for a complete working description

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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
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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 Egans Fundamentals of Respiratory Care,
  Eighth Edition for a complete working description

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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

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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

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Regulators and Flowmeters

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

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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)

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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

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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

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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

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Regulators and Flowmeters

• Bourdon Gage
• Not back-pressure compensated
• As resistance to flow increases, the indicated
  flow reading becomes inaccurate

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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 Egans Fundamentals of Respiratory Care,
  Eighth Edition for a complete working description

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Regulators and Flowmeters

• Thorpe Tube
• Two types
• Pressure uncompensated vs. Pressure compensated

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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

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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 flowmeters
  performance. The float will be an actual reading
  of flow delivered

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Regulators and Flowmeters

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

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Regulators and Flowmeters

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

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Regulators and Flowmeters

• Ranges of Flowmeters
• Standard
• 0 15 L/min (1-L/min interval)
• Most oxygen delivery devices

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Regulators and Flowmeters

• Correctly Reading a Flowmeter
• Ball-float flowmeter
• Read from the middle of the ball

6 L/min
2 L/min
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Regulators and Flowmeters

• Correctly Reading a Flowmeter
• Bobbin flowmeter
• Read from the top of the bobbin

2 L/min
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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)

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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.
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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
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Regulators and Flowmeters

• Attaching a Regulator to a Gas Cylinder
• Select the proper gas cylinder
• Ensure content of cylinder by checking the label

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Regulators and Flowmeters

• Attaching a Regulator to a Gas Cylinder
• Remove protective covering from cylinder outlet

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Regulators and Flowmeters

• Attaching a Regulator to a Gas Cylinder
• Crack the cylinder to remove dust, debris and
  moisture

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Regulators and Flowmeters

• Attaching a Regulator to a Gas Cylinder
• Select the appropriate gas regulator
• Ensure that a plastic washer is in place

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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!!!

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Regulators and Flowmeters

• Attaching a Regulator to a Gas Cylinder
• Tighten the fittings in place

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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
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Regulators and Flowmeters

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

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Regulators and Flowmeters

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

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Regulators and Flowmeters

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