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