Choose a different country or region to see the content specific to your location

Continue

Select Your Country/Region

Current Region: Global (EN)

Asia

AfghanistanAfghanistan(EN)
BahrainBahrain(EN)
BangladeshBangladesh(EN)
BhutanBhutan(EN)
Brunei DarussalamBrunei Darussalam(EN)
CambodiaCambodia(EN)
ChinaChina(ZH)
ChinaChina(EN)
Hong Kong ChinaHong Kong China(EN)
Hong Kong ChinaHong Kong China(ZH)
IndiaIndia(EN)
IndonesiaIndonesia(EN)
IraqIraq(EN)
IsraelIsrael(EN)
JapanJapan(EN)
JordanJordan(EN)
KazakhstanKazakhstan(EN)
KuwaitKuwait(EN)
KyrgyzstanKyrgyzstan(EN)
LaosLaos(EN)
LebanonLebanon(EN)
MalaysiaMalaysia(EN)
NepalNepal(EN)
OmanOman(EN)
PakistanPakistan(EN)
PhilippinesPhilippines(EN)
QatarQatar(EN)
Saudi ArabiaSaudi Arabia(EN)
SingaporeSingapore(EN)
South KoreaSouth Korea(EN)
Sri LankaSri Lanka(EN)
TaiwanTaiwan(ZH)
TaiwanTaiwan(EN)
TajikistanTajikistan(EN)
ThailandThailand(EN)
TurkeyTurkey(EN)
United Arab EmiratesUnited Arab Emirates(EN)
UzbekistanUzbekistan(EN)
VietnamVietnam(EN)
YemenYemen(EN)

Africa

AlgeriaAlgeria(FR)
AlgeriaAlgeria(EN)
AngolaAngola(EN)
BeninBenin(EN)
BotswanaBotswana(EN)
Burkina-FasoBurkina-Faso(EN)
BurundiBurundi(EN)
ComorosComoros(EN)
Dem Rep of CongoDem Rep of Congo(EN)
DjiboutiDjibouti(EN)
EgyptEgypt(EN)
EritreaEritrea(EN)
EthiopiaEthiopia(EN)
GabonGabon(EN)
GambiaGambia(EN)
GhanaGhana(EN)
GuineaGuinea(EN)
Guinea-BissauGuinea-Bissau(EN)
KenyaKenya(EN)
LesothoLesotho(EN)
LiberiaLiberia(EN)
LibyaLibya(EN)
MadagascarMadagascar(EN)
MalawiMalawi(EN)
MaliMali(EN)
MauritaniaMauritania(EN)
MauritiusMauritius(EN)
MoroccoMorocco(EN)
MozambiqueMozambique(EN)
NamibiaNamibia(EN)
NigerNiger(EN)
NigeriaNigeria(EN)
RwandaRwanda(EN)
Sao Tome and PrincipeSao Tome and Principe(EN)
SenegalSenegal(EN)
SeychellesSeychelles(EN)
Sierra LeoneSierra Leone(EN)
SomaliaSomalia(EN)
South AfricaSouth Africa(EN)
SwazilandSwaziland(EN)
TanzaniaTanzania(EN)
TogoTogo(EN)
TunisiaTunisia(FR)
TunisiaTunisia(EN)
UgandaUganda(EN)
ZambiaZambia(EN)
ZimbabweZimbabwe(EN)

Europe

AustriaAustria(EN)
BelgiumBelgium(EN)
BelgiumBelgium(FR)
Czech RepublicCzech Republic(EN)
FinlandFinland(EN)
FranceFrance(EN)
FranceFrance(FR)
GermanyGermany(EN)
ItalyItaly(EN)
NetherlandsNetherlands(EN)
PolandPoland(EN)
RussiaRussia(EN)
SlovakiaSlovakia(EN)
SpainSpain(EN)
SpainSpain(ES)
SwedenSweden(EN)
SwitzerlandSwitzerland(EN)
SwitzerlandSwitzerland(FR)
United KingdomUnited Kingdom(EN)
AlbaniaAlbania(EN)
ArmeniaArmenia(EN)
AzerbaijanAzerbaijan(EN)
BelarusBelarus(EN)
BosniaBosnia(EN)
BulgariaBulgaria(EN)
CroatiaCroatia(EN)
CyprusCyprus(EN)
DenmarkDenmark(EN)
EstoniaEstonia(EN)
GeorgiaGeorgia(EN)
GreeceGreece(EN)
HungaryHungary(EN)
IcelandIceland(EN)
LatviaLatvia(EN)
LiechtensteinLiechtenstein(EN)
LithuaniaLithuania(EN)
LuxembourgLuxembourg(EN)
LuxembourgLuxembourg(FR)
MacedoniaMacedonia(EN)
MaltaMalta(EN)
MonacoMonaco(EN)
MongoliaMongolia(EN)
MontenegroMontenegro(EN)
NorwayNorway(EN)
PortugalPortugal(EN)
RomaniaRomania(EN)
San MarinoSan Marino(EN)
SloveniaSlovenia(EN)
TurkeyTurkey(EN)
UkraineUkraine(EN)
IrelandIreland(EN)
SerbiaSerbia(EN)

North America

USAUSA(EN)
USAUSA(ES)
CanadaCanada(FR)
CanadaCanada(EN)
MexicoMexico(EN)
MexicoMexico(ES)
Antigua and BarbudaAntigua and Barbuda(EN)
BahamasBahamas(EN)
BarbadosBarbados(EN)
BelizeBelize(EN)
Costa RicaCosta Rica(ES)
DominicaDominica(EN)
Dominican RepublicDominican Republic(ES)
El SalvadorEl Salvador(ES)
GrenadaGrenada(EN)
GuatemalaGuatemala(ES)
HaitiHaiti(EN)
HondurasHonduras(ES)
JamaicaJamaica(EN)
NicaraguaNicaragua(ES)
PanamaPanama(EN)
PanamaPanama(ES)
Puerto RicoPuerto Rico(ES)
Saint Vincent and the GrenadinesSaint Vincent and the Grenadines(EN)
St Kitts and NevisSt Kitts and Nevis(EN)
St LuciaSt Lucia(EN)
Trinidad and TobagoTrinidad and Tobago(EN)

Oceania

AustraliaAustralia(EN)
KiribatiKiribati(EN)
New ZealandNew Zealand(EN)
Papua New GuineaPapua New Guinea(EN)
East TimorEast Timor(EN)

South America

ArgentinaArgentina(EN)
ArgentinaArgentina(ES)
BoliviaBolivia(ES)
BrazilBrazil(EN)
ChileChile(ES)
ColombiaColombia(ES)
ColombiaColombia(EN)
EcuadorEcuador(ES)
GuyanaGuyana(EN)
ParaguayParaguay(ES)
PeruPeru(EN)
PeruPeru(ES)
SurinameSuriname(EN)
UruguayUruguay(EN)
UruguayUruguay(ES)
Global (EN)
Our Offices
Contact Us
About Us
Resources
Find a Sales Rep
miltonroy
  • Products
    • Chemical Pumps
      • G Series/MACROY®
      • CENTRAC™ Series
      • MAXROY® Series
      • MILROYAL® Series
      • mROY® Series
        • mRoy MRA Series
        • mRoy MRB Series
        • mRoy XT Series
        • mRoy XW Series
        • mRoy XA and XB Series
      • PRIMEROYAL® Series
        • PH Model
        • PK and PKG Model
        • PL and PLG Model
        • PN Model
        • PP Model
        • PR Model
        • PX FT Model
        • PX Model
      • PROTEUS™ Series
    • Process Pumps
      • Megaroyal®
      • Poweroyal®
    • Mixers
      • Top-Entry Mixers
        • Helisem® Series
        • HM Series
        • ROBIN®
      • Side-Entry Mixers
      • An Overview of Low Shear Mixers
    • EMAG Electro Magnetic (EMAG)
    • Electronics and Metering
      • Electronics and Metering
      • The Basics of Streaming Current Detectors
    • Valves and Accessories
  • Systems
    • Chemical Injection Package
    • Dosaskid®
    • Dosaskid®
    • POLYPACK®
    • STO Chemical Dosing Skids
  • Industries & Applications
    • Energy
      • Oil & Gas
        • Crude Oil Storage
        • Drag Reducer Agents (DRA)
        • Chemical Injection
      • Power Generation
      • Renewables
        • Renewable Diesel
      • Petrochemical
        • Catalyst Reactor Charge Pumping
        • Chemical
        • General Industry
        • Polymer Solutions
    • Industrial
      • Agriculture
        • Indoor Farming
    • Water Treatment
      • Potable Water
        • Rapid Mixing in Water Treatment
        • Surface Water Treatment
      • Process Water
      • Wastewater
        • Municipal Water & Waste Treatment
        • Wastewater Treatment
    • Lithium Mining
  • Technologies
    • Chemical Injection in O&G
    • Metering Pump Principles
      • Metering Pump Principles
      • Part 2: Liquid Ends
      • Part 3: Metallic Diaphragm and Critical Service
      • Part 4: High Performance Diaphragm
    • Tank Mixers - BS&W
    • Turndown Ratio in Metering Pumps
    • The Basics of Streaming Current Detectors
    • Lithium Mining
    • The Basics of Process Pumps
    • The Basics of Reciprocating Pumps
    • Renewable Diesel
    • Rapid Mixing in Water Treatment
  • Aftermarket & Support
    • CARE Maintenance Plans
    • Aftermarket & Support
      • Services
      • Ressources
      • Formation
    • Register Your Products
  • Products
    • Chemical Pumps
      • G Series/MACROY®
      • CENTRAC™ Series
      • MAXROY® Series
      • MILROYAL® Series
      • mROY® Series
      • PRIMEROYAL® Series
      • PROTEUS™ Series
    • Process Pumps
      • Megaroyal®
      • Poweroyal®
    • Mixers
      • Top-Entry Mixers
      • Side-Entry Mixers
      • An Overview of Low Shear Mixers
    • EMAG
    • Electronics and Metering
      • Electronics and Metering
      • The Basics of Streaming Current Detectors
    • Valves and Accessories
  • Systems
    • Chemical Injection Package
    • Dosaskid®
    • Dosaskid®
    • POLYPACK®
    • STO Chemical Dosing Skids
  • Industries & Applications
    • Energy
      • Oil & Gas
      • Power Generation
      • Renewables
      • Petrochemical
    • Industrial
      • Agriculture
    • Water Treatment
      • Potable Water
      • Process Water
      • Wastewater
    • Lithium Mining
  • Technologies
    • Chemical Injection in O&G
    • Metering Pump Principles
      • Metering Pump Principles
      • Part 2: Liquid Ends
      • Part 3: Metallic Diaphragm and Critical Service
      • Part 4: High Performance Diaphragm
    • Tank Mixers - BS&W
    • Turndown Ratio in Metering Pumps
    • The Basics of Streaming Current Detectors
    • Lithium Mining
    • The Basics of Process Pumps
    • The Basics of Reciprocating Pumps
    • Renewable Diesel
    • Rapid Mixing in Water Treatment
  • Aftermarket & Support
    • CARE Maintenance Plans
    • Aftermarket & Support
      • Services
      • Ressources
      • Formation
    • Register Your Products
  • Contact Us
  • About Us
  • Resources
  • Find a Sales Rep
  • Global (EN) -
    • Asia
      • SpacerAfghanistan(EN)
      • SpacerBahrain(EN)
      • SpacerBangladesh(EN)
      • SpacerBhutan(EN)
      • SpacerBrunei Darussalam(EN)
      • SpacerCambodia(EN)
      • SpacerChina(ZH)
      • SpacerChina(EN)
      • SpacerHong Kong China(EN)
      • SpacerHong Kong China(ZH)
      • SpacerIndia(EN)
      • SpacerIndonesia(EN)
      • SpacerIraq(EN)
      • SpacerIsrael(EN)
      • SpacerJapan(EN)
      • SpacerJordan(EN)
      • SpacerKazakhstan(EN)
      • SpacerKuwait(EN)
      • SpacerKyrgyzstan(EN)
      • SpacerLaos(EN)
      • SpacerLebanon(EN)
      • SpacerMalaysia(EN)
      • SpacerNepal(EN)
      • SpacerOman(EN)
      • SpacerPakistan(EN)
      • SpacerPhilippines(EN)
      • SpacerQatar(EN)
      • SpacerSaudi Arabia(EN)
      • SpacerSingapore(EN)
      • SpacerSouth Korea(EN)
      • SpacerSri Lanka(EN)
      • SpacerTaiwan(ZH)
      • SpacerTaiwan(EN)
      • SpacerTajikistan(EN)
      • SpacerThailand(EN)
      • SpacerTurkey(EN)
      • SpacerUnited Arab Emirates(EN)
      • SpacerUzbekistan(EN)
      • SpacerVietnam(EN)
      • SpacerYemen(EN)
    • Africa
      • SpacerAlgeria(FR)
      • SpacerAlgeria(EN)
      • SpacerAngola(EN)
      • SpacerBenin(EN)
      • SpacerBotswana(EN)
      • SpacerBurkina-Faso(EN)
      • SpacerBurundi(EN)
      • SpacerComoros(EN)
      • SpacerDem Rep of Congo(EN)
      • SpacerDjibouti(EN)
      • SpacerEgypt(EN)
      • SpacerEritrea(EN)
      • SpacerEthiopia(EN)
      • SpacerGabon(EN)
      • SpacerGambia(EN)
      • SpacerGhana(EN)
      • SpacerGuinea(EN)
      • SpacerGuinea-Bissau(EN)
      • SpacerKenya(EN)
      • SpacerLesotho(EN)
      • SpacerLiberia(EN)
      • SpacerLibya(EN)
      • SpacerMadagascar(EN)
      • SpacerMalawi(EN)
      • SpacerMali(EN)
      • SpacerMauritania(EN)
      • SpacerMauritius(EN)
      • SpacerMorocco(EN)
      • SpacerMozambique(EN)
      • SpacerNamibia(EN)
      • SpacerNiger(EN)
      • SpacerNigeria(EN)
      • SpacerRwanda(EN)
      • SpacerSao Tome and Principe(EN)
      • SpacerSenegal(EN)
      • SpacerSeychelles(EN)
      • SpacerSierra Leone(EN)
      • SpacerSomalia(EN)
      • SpacerSouth Africa(EN)
      • SpacerSwaziland(EN)
      • SpacerTanzania(EN)
      • SpacerTogo(EN)
      • SpacerTunisia(FR)
      • SpacerTunisia(EN)
      • SpacerUganda(EN)
      • SpacerZambia(EN)
      • SpacerZimbabwe(EN)
    • Europe
      • SpacerAustria(EN)
      • SpacerBelgium(EN)
      • SpacerBelgium(FR)
      • SpacerCzech Republic(EN)
      • SpacerFinland(EN)
      • SpacerFrance(EN)
      • SpacerFrance(FR)
      • SpacerGermany(EN)
      • SpacerItaly(EN)
      • SpacerNetherlands(EN)
      • SpacerPoland(EN)
      • SpacerRussia(EN)
      • SpacerSlovakia(EN)
      • SpacerSpain(EN)
      • SpacerSpain(ES)
      • SpacerSweden(EN)
      • SpacerSwitzerland(EN)
      • SpacerSwitzerland(FR)
      • SpacerUnited Kingdom(EN)
      • SpacerAlbania(EN)
      • SpacerArmenia(EN)
      • SpacerAzerbaijan(EN)
      • SpacerBelarus(EN)
      • SpacerBosnia(EN)
      • SpacerBulgaria(EN)
      • SpacerCroatia(EN)
      • SpacerCyprus(EN)
      • SpacerDenmark(EN)
      • SpacerEstonia(EN)
      • SpacerGeorgia(EN)
      • SpacerGreece(EN)
      • SpacerHungary(EN)
      • SpacerIceland(EN)
      • SpacerLatvia(EN)
      • SpacerLiechtenstein(EN)
      • SpacerLithuania(EN)
      • SpacerLuxembourg(EN)
      • SpacerLuxembourg(FR)
      • SpacerMacedonia(EN)
      • SpacerMalta(EN)
      • SpacerMonaco(EN)
      • SpacerMongolia(EN)
      • SpacerMontenegro(EN)
      • SpacerNorway(EN)
      • SpacerPortugal(EN)
      • SpacerRomania(EN)
      • SpacerSan Marino(EN)
      • SpacerSlovenia(EN)
      • SpacerTurkey(EN)
      • SpacerUkraine(EN)
      • SpacerIreland(EN)
      • SpacerSerbia(EN)
    • North America
      • SpacerUSA(EN)
      • SpacerUSA(ES)
      • SpacerCanada(FR)
      • SpacerCanada(EN)
      • SpacerMexico(EN)
      • SpacerMexico(ES)
      • SpacerAntigua and Barbuda(EN)
      • SpacerBahamas(EN)
      • SpacerBarbados(EN)
      • SpacerBelize(EN)
      • SpacerCosta Rica(ES)
      • SpacerDominica(EN)
      • SpacerDominican Republic(ES)
      • SpacerEl Salvador(ES)
      • SpacerGrenada(EN)
      • SpacerGuatemala(ES)
      • SpacerHaiti(EN)
      • SpacerHonduras(ES)
      • SpacerJamaica(EN)
      • SpacerNicaragua(ES)
      • SpacerPanama(EN)
      • SpacerPanama(ES)
      • SpacerPuerto Rico(ES)
      • SpacerSaint Vincent and the Grenadines(EN)
      • SpacerSt Kitts and Nevis(EN)
      • SpacerSt Lucia(EN)
      • SpacerTrinidad and Tobago(EN)
    • Oceania
      • SpacerAustralia(EN)
      • SpacerKiribati(EN)
      • SpacerNew Zealand(EN)
      • SpacerPapua New Guinea(EN)
      • SpacerEast Timor(EN)
    • South America
      • SpacerArgentina(EN)
      • SpacerArgentina(ES)
      • SpacerBolivia(ES)
      • SpacerBrazil(EN)
      • SpacerChile(ES)
      • SpacerColombia(ES)
      • SpacerColombia(EN)
      • SpacerEcuador(ES)
      • SpacerGuyana(EN)
      • SpacerParaguay(ES)
      • SpacerPeru(EN)
      • SpacerPeru(ES)
      • SpacerSuriname(EN)
      • SpacerUruguay(EN)
      • SpacerUruguay(ES)

This site uses some unobtrusive cookies to store information on your computer. By using the website, you hereby agree on cookies storage.
OK Cookie Policy

Turndown Ratio and Metering Pumps

Contact Us
Request a Quote
Request Service, Parts or Support
Find a Sales Rep

Turndown Ratio and Metering Pumps

Metering pumps are reciprocating positive displacement chemical dosing devices with the ability to vary capacity manually or automatically as process conditions require.These pumps are used in applications requiring highly accurate, repeatable and adjustable rate of flow.

turndown-ratio-and-metering-pumps_content2

Related product with turndown capabilities



Metering pumps are characterized by their ability to meet specific performance requirements concerning linearity, steady state accuracy, and repeatability. Turndown (the adjustable range of a metering pump) and Accuracy are the key to defining the quality and performance of a metering pump.

 

Turndown Ratio is the rated capacity divided by the minimum capacity that can be obtained while maintaining specified steady state accuracy and linearity.

 

Example
Rated Capacity: 50 Gallons per Hour
Minimum Capacity: 5 Gallons per Hour
Turndown: 50 / 5 = 10
Turndown Ratio: 10:1

 

In the above example, the turntown ratio is 10:1. If minimum capacity was 0.5 GPH, the turndown ratio would be 100:1. However, defining turndown without accuracy is meaningless.

 

Consider the same pump rated at 50 GPH maximum capacity. If you don't define accuracy, technically the pump can be turned down to 0 GPH, in which case the value is infinite.

 

Defining Accuracy requires two inputs:

  • The percentage range expressed as a ±value
  • A qualifier that actually defines what true value is of the stated percentage

 

Metering pumps usually have an accuracy of ±1%. Manufacturers use full range/scale, steady state at set point or repetitive as a qualifier to define accuracy. Steady state at set point is the only useful qualifier of the accuracy percentage range for a metering pump. Let us look at each qualifier in detail and why steady state at set point is the best qualifier.

 

Full Range or Full Scale Accuracy
Uses the maximum capacity of the pump as a valve. In our example above:

  • Accuracy of ± 1% of full scale
    ○ 1% of full scale = 0.5 GPH
  • Accuracy at 100% capacity setting (50 GPH)
    ○ 50 GPM ± 0.5 GPH
    ○ 0.5 / 50 = 1% of set point
  • Accuracy of 10% capacity setting (5 GPH)
    ○ 5 GPH ± 0.5 GPH
    ○ 0.5 / 5 = 10% of set point

 

Full scale accuracy is not very accurate. From our 50 GPH example above, 1% of full scale = 0.5 GPH. No matter where we set the pump’s capacity, its flow specification allows an error of plus or minus 0.5 GPH, which in total is actually twice that because it’s ±. So the error range is 1 GPH.

 

When the pump is set at 100% capacity, it is an easy to understand calculation because it equals ± 1%. However when the pump is set at 10% capacity, the allowable variation is still equal to 1% of the maximum capacity. So the user expects 5 GPH, but with a possible ± error of 0.5 GPH. The actual allowable deviation, by specification, is now ± 10% of the pump's set point – an error range equal to 20% of the pump's setting. This is not metering pump accuracy. To achieve accuracy the Steady State at Set Point must be set.

 

Steady State at Set Point Accuracy
Uses the current capacity setting of the pump as the value. From above example:
At 100% capacity setting, 1% = 0.5 GPH
At 10% capacity setting, 1% = 0.05 GPH

 

Steady state accuracy is the only useful accuracy for a metering pump. It’s measured at the pump’s current capacity setting. The value of the flow changes based on the capacity setting because the percentage is based on the setting, not the maximum pump rating.

Chart 1

Chart 1 shows the upper and lower limit of a metering pump with ± 1% steady state accuracy. The margin for acceptable deviation is very narrow – and that’s a true controlled volume metering pump as defined by hydraulic institute, ANSI, and API.

 

Repetitive Accuracy
Repetitive accuracy has 2 meanings:

  • Accuracy of the pump continuously operating at the same capacity setting
  • Accuracy of the pump at a specific setting when capacity is changed, and then returned to the original setting

 

Repetitive accuracy is also often misused. It’s not really an overall statement of pump accuracy that would be tied to turndown. It’s only relationship to turndown is that the repetitive accuracy only applies within the turndown range.

 

The purpose of a metering pump is to deliver predictable flow at a capacity setting, so definition 2 applies. Definition 1 means very little because it does not really challenge the pump's ability to be predictably accurate over its full range. That is why definition 1 is often applied to pumps that are not really metering pumps. API and other standards organizations define ± 3% as the specification for repetitive accuracy, and expect the pump will be tested according to definition 2.

 

In conclusion, it should be clear that you cannot separate turndown from accuracy, and that steady state accuracy is the only form of an accuracy statement that has values in a metering pump application. It is measurable, verificable, and adds value to the pumping system.

 

A true controlled volume metering pump meets stringent agency standards for turndown and steady state accuracy.

 

turndown-ratio-and-metering-pumps_turndown-whitepaper


Learn the Proper Way to Measure a Metering Pump’s Turndown

Learn the Proper Way to Measure a Metering Pump’s Turndown

What is turndown and how is it accurately measured? Download our educational white paper to learn why knowing the true turndown of a pump is essential, especially when it comes to metering pumps. Milton Roy’s experts will not only explain the proper ways of measuring turndown, but they will also tell you about the turndown myths you should avoid.


Learn more

RELATED PRODUCTS

Critical Process Control mRoy MRA Series

mRoy Series Chemical Pumps

mROY series metering pumps control chemical dosing with unmatched accuracy and reliability.

Learn More

Metering Pumps Proteus Series Metering Pumps

PROTEUS™ Series
chemical Pumps

New Communications Model Offers Tighter Process Control and Enhanced Plant Automation

Learn More

Metering Pumps CENTRAC Series Metering Pumps

CENTRAC™ Series
Chemical Pumps

CENTRAC metering pumps are engineered to operate with the highest level of performance and accuracy.

Learn More

  • Contact Us
  • Worldwide Locations
  • About Ingersoll Rand
  • Privacy Policy
  • Legal Information
  • Our Other Brands
  • Albin Pump
  • ARO Pumps
  • Dosatron
  • Linc
  • Williams
  • LMI
  • Haskel
  • YZ Systems
  • Hartell
  • Albin Pump
  • ARO Pumps
  • Dosatron
  • Linc
  • Williams
  • LMI
  • Haskel
  • YZ Systems
  • Hartell

Explore our family of brands

© Ingersoll Rand, is a diverse and inclusive environment. We are an equal opportunity employer and are dedicated to hiring qualified protected veterans and individuals with disabilities.

Privacy Policy