reduc vals, reguls flowmtrs bb 10.11
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REDUCING VALVES, REDUCING VALVES, REGULATORS & FLOWMETERSREGULATORS & FLOWMETERS
DEFINITIONSDEFINITIONS
Reducing valve – a valve that reduces a Reducing valve – a valve that reduces a higher pressure to a lower pressurehigher pressure to a lower pressure
Flowmeter- a device that controls & Flowmeter- a device that controls & indicates flowindicates flow
Regulator – a reducing valve & a Regulator – a reducing valve & a flowmeterflowmeter
Reducing Valves? What’s Reducing Valves? What’s important?important?
These types of valves decrease high These types of valves decrease high pressures - 2200 psi to working pressure - pressures - 2200 psi to working pressure - 50 psi for most respiratory therapy 50 psi for most respiratory therapy equipmentequipment
Also used to decrease the bulk storage Also used to decrease the bulk storage pressure to 50 psipressure to 50 psi
Reducing valves (regulators) Reducing valves (regulators) ClassificationClassification
Single-stage regulator- two opposing Single-stage regulator- two opposing forces (spring tension and gas pressure) forces (spring tension and gas pressure) are separated by a thin diaphragmare separated by a thin diaphragm The diaphragm is straight & the inlet valve is The diaphragm is straight & the inlet valve is
closed when the forces are equalclosed when the forces are equal The spring tension (for resp. set @ 50 psi The spring tension (for resp. set @ 50 psi
but may be adjustable) should be equal to but may be adjustable) should be equal to the gas pressure, but when the gas pressure the gas pressure, but when the gas pressure drops, the inlet opens and gas enters and drops, the inlet opens and gas enters and equilibrates to the spring tensionequilibrates to the spring tension
Multi-stage RegulatorsMulti-stage Regulators
Utilizes two or more single stage regulators in a Utilizes two or more single stage regulators in a seriesseries Double stage – 2200 psi to 700 psi to 50 psiDouble stage – 2200 psi to 700 psi to 50 psi Triple – 2200 psi to 700 psi to 300 psi to 50 psiTriple – 2200 psi to 700 psi to 300 psi to 50 psi Multistage are more precise and have more “laminar” Multistage are more precise and have more “laminar”
flowflow
EACH STAGE MUST HAVE A POP-OFF VALVE TO EACH STAGE MUST HAVE A POP-OFF VALVE TO RELEASE EXCESS PRESSURERELEASE EXCESS PRESSURE
COUNT THE POP-OFFS TO IDENTIFY THE # OF COUNT THE POP-OFFS TO IDENTIFY THE # OF STAGESSTAGES
Preset Reducing ValvePreset Reducing Valve
A Gas inletA Gas inlet
B GaugeB Gauge
C High pressure chamberC High pressure chamber
D Low pressure chamberD Low pressure chamber
E DiaphragmE Diaphragm
F SpringF Spring
G Valve stemG Valve stem
H Inlet valveH Inlet valve
I Gas outletI Gas outlet
L Safety ventL Safety vent
Adjustable Reducing ValveAdjustable Reducing Valve
Bourdon GaugeBourdon Gauge
It’s a Bourdon Gauge!! But how It’s a Bourdon Gauge!! But how does it work?does it work?
Basically, pressure enters a chamber that has a Basically, pressure enters a chamber that has a fixed orifice outlet. As the pressure is increased, fixed orifice outlet. As the pressure is increased, the coiled copper tube straightens out and the the coiled copper tube straightens out and the needle valve turns to read a higher unit.needle valve turns to read a higher unit.
Bourdon gauges can be calibrated to read Bourdon gauges can be calibrated to read pressurepressure – Bourdon regulator – Bourdon regulator
Or a Or a Bourdon gaugeBourdon gauge can be calibrated to can be calibrated to flowflow- a - a Bourdon flowmeterBourdon flowmeter
Bourdon GaugeBourdon Gauge
Bourdon springBourdon spring
Thorpe tubesThorpe tubes
Thorpe-Tube FlowmetersThorpe-Tube Flowmeters2 Types2 Types
1. Non-back pressure compensated thorpe-1. Non-back pressure compensated thorpe-tube flowmetertube flowmeter The needle valve is before the tube indicatorThe needle valve is before the tube indicator The thorpe-tube is not pressurized to 50 psiThe thorpe-tube is not pressurized to 50 psi Back pressure will cause the float to drop and Back pressure will cause the float to drop and
the patient will receive more flow than the the patient will receive more flow than the tube indicatestube indicates
Thorpe-tube flowmeters Thorpe-tube flowmeters CompensatedCompensated
2. Pressure-compensated Thorpe-tube 2. Pressure-compensated Thorpe-tube flowmeterflowmeter Needle-valve (flow control) located distal to Needle-valve (flow control) located distal to
the Thorpe-tubethe Thorpe-tube Pressure in tube is pressurized to 50 psiPressure in tube is pressurized to 50 psi If resistance is placed downstream from the If resistance is placed downstream from the
Thorpe-tube the flow will read accurateThorpe-tube the flow will read accurate
UncompensatedUncompensated CompensatedCompensated
How to tell the difference?How to tell the difference?
1. The label1. The label
2. “Test” With the needle valve turned off, 2. “Test” With the needle valve turned off, place the flowmeter in a 50 psi gas place the flowmeter in a 50 psi gas source, if pressure-compensated, the source, if pressure-compensated, the float will jump up and fall back to zerofloat will jump up and fall back to zero
3.3. Location of the needle valve ?Location of the needle valve ?
4.4. Occlude outlet and read flow?Occlude outlet and read flow?
FLOW RANGE FOR FLOW RANGE FOR FLOWMETERSFLOWMETERS
Usually a flowmeter is incremented up to 15 Usually a flowmeter is incremented up to 15 L /minL /min
This varies-This varies- Neonate – mL/minNeonate – mL/min Incremented up to 3 L/minIncremented up to 3 L/min Pediatrics up to 8 L/minPediatrics up to 8 L/min
Some adult flowmeters go up to 25 L/minSome adult flowmeters go up to 25 L/min
BOURDON FLOWMETERBOURDON FLOWMETER
A reducing valve that controls the A reducing valve that controls the pressurepressure gradient thru a fixed orifice gradient thru a fixed orifice
As the driving pressure increases the flow As the driving pressure increases the flow exiting the orifice increasesexiting the orifice increases
NOT-pressure compensatedNOT-pressure compensated If back pressure is placed downstream, If back pressure is placed downstream,
the meter will read higher than what is the meter will read higher than what is exiting the orificeexiting the orifice
regulatorsregulators
1. Thorpe-tube type- has to stay vertical1. Thorpe-tube type- has to stay vertical
2. Bourdon type- good for transports2. Bourdon type- good for transports
FLOW RESTRICTORS – FLOW RESTRICTORS – functions like a Bourdonfunctions like a Bourdon
Type 1 –Fixed-orifice Type 1 –Fixed-orifice
Type II – Adjustable-Type II – Adjustable-orifice orifice
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