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Fluid Flow Control - Dosing / Metering Pump

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Dosing / Metering Pump Dosing / Metering Pump

LP Dosing Pump Pulsation Dampening

Solenoid dosing pumps and lost motion cam drive dosing pumps need a damper to catch the sudden impulses that these pumps make.

More detailed information:
Pumping Technik: Dosing Pumps, Solenoid Digital, with Pulsation Dampers
Costings Info: LP Dosing Pumps
Contact / RFQ: Pulsation Dampener Inquiry / What do you need?

HP Metering Pump Pulsation Dampening

Diaphragm pumps high pressure with multi-layer PTFE are matched with similar PTFE diaphragm pulse dampers having secondary containment sealing.

More detailed information:
Pumping Technik: Multihead Diaphragm Pumps
Pumping Technik: Multihead Diaphragm Pumps / Single Connection
Pumping Technik: Diaphragm Head Pumps Pulsation Dampners
Pumping Technik: Process Diaphragm Pumps / Metering Pumps
Costings Info: HP Metering Pumps
Contact / RFQ: Pulsation Dampener Inquiry / What do you need?

Hydroflo / Aquflow

A Div. of Precision Flow Technologies, Inc.

Hydroflo metering pump line is currently being manufactured under the name AquFlow in Irvine, CA. After acquiring the Hydroflo pump line in 2007 AquFlow added several resources to increase the level of support for getting service parts and replacement pumps quickly. While the original design, tooling and manufacturing has remained the same these processes have been streamlined to reduce the response time drastically. It is not uncommon now to get replacement parts shipped the same day and replacement pumps shipped in 2-3 days. The quality and dependability is still the same where many of these pumps have lasted for decades with minimal maintenance.

Available in flow capacities up to 3,500 Gallons / hour and pressures up to 4000 psi, the AquFlow (formerly Hydroflo) hydraulic diaphragm metering pump line can be made out of corrosion resistant materials such as 316 Stainless Steel, Alloy 20, Hastelloy C, PVC, PVDF and PTFE.

A new line of Solenoid metering pump has also been added to make a complete offering for applications in various industries such as Water and Wastewater treatment, chemical processing, Oil & Gas, Fireproofing, Fertigation etc.

See also: Aquflow - General Brochure.pdf
See also: AquFlow -Revitalized Hydroflo.pdf

Product(s) / Service(s): HYDROFLO METERING PUMP
Source / Origin of Design: unknown
Contact Information:
17865 Skypark Circle
Suite M
Irvine, CA 92614
Phone: 949-757-1753
Fax: 949-757-1687
Email: sales@aquflow.com
View internet links for Hydroflo / Aquflow >>>

Fluid Metering Inc

FMI pioneered the first patented valveless rotating and reciprocating piston metering pump concept and has been providing precise fluid control for over 44 years. FMI dispensers and metering pumps have been utilized in a broad range of laboratory, analytical, industrial process, and OEM applications requiring precision fluid control.

Product(s) / Service(s): MICRO METERING VALVELESS, CERAMIC ROTATING PLUNGER
Source / Origin of Design: unknown
Contact Information:
1-800-223-3388
1-516-922-6050
Fax: 1-516-624-8261
View internet links for Fluid Metering Inc >>>

Dosapro Milton Roy Europe

For over 70 years, Milton Roy Company has manufactured controlled volume (metering) pumps and related equipment to handle a wide variety of fluids. Our products are sold internationally with two goals in mind: integrating our equipment into larger systems that meet the needs of local and multi-national companies in the water and wastewater treatment markets, hydrocarbon processing industries, oil & gas and in power generation; identifying new markets and applications for our products.

Product(s) / Service(s): metering pumps
Source / Origin of Design: unknown
Contact Information:
10 Grande Rue
27360 Pont Saint Pierre - France
Tél. : +33.(0)2.32.68.30.00
Fax : +33.(0)2.32.68.30.93
contact@miltonroy-europe.com
View internet links for Dosapro Milton Roy Europe >>>

American Lewa Inc.

Ott Holding International GmbH from Leonberg, PTFE sandwich diaphragm.

Product(s) / Service(s): pumps
Source / Origin of Design: unknown
Contact Information:
11011 Richmond Ave. Suite 250
Houston, TX 77042 
View internet links for American Lewa Inc. >>>

Bran+Luebbe

Bran & Luebbe subsid SPX corp - "NOVADOS" & "NOVAPLEX", PTFE double layer diaphragm. Bran+Luebbe offers you an unrivalled range of metering pumps for practically every situation where liquids have to be metered and blended. The product range includes leakage-free diaphragm pumps as well as plunger pumps.

Comments: Pumps, Systems and Analyzers
Company: Bran + Luebbe GmbH
Address: Werkstraße 4 22844 Norderstedt Germany
Phone: 0049 - 40 -522 02-0
Fax: 0049 - 40 - 522 02-444
Email Address: info.germany@processequipment.spx.com

Comments: Pumps and Systems
Company: Bombas Bornemann S.R.L
Address: Armenia 2898 1605 Munro PCIA./Buenos Aires Argentina
Phone: (00 54) 11 - 47 56 80 08
Fax: (00 54) 11 - 47 56 55 41

Comments: Pumps and Systems
Company: Coditec Maquinaria Ltda.
Address: Casilla 22, Centro de Casillas Santiago 1 Chile, Ra 0333 Chile
Phone: (00 56) 2 - 6 34 16 43
Fax: (00 56) 2 - 6 34 46 22

Comments: Pumps and Systems
Company: Lufran C.A.
Address: Av. Principal de los Ruices Centro Empresarial Los Ruices piso 1. ofc. 109, Lo Venezuela

Comments: Analyzer (Continuous-Flow Analyzer only)
Company: CETEC Equip. para Lab. Ltda
Address: Av. Senador Cesar Vergueiro, 796 14020-510 - Ribeirao Preto - SP Brazil
Phone: (00 55) 16 3916 6000
Fax: (00 55) 16 3916 6000
Email Address: cetec-lab@cetec-lab.com.br

Comments: Pumps and Systems
Company: Ivan Bohmann C.A.
Address: Casilla 1317 Guayaquil Ecuador, Km 3084 Bohma Ecuador
Phone: (00 593) 4 - 25 - 41 11
Fax:(00 593) 4 - 25 - 41 59

Comments: Pumps, Systems and Metering Systems for Oil and Gas
Company: AB Zander & Ingeström
Address: Box 502 169 29 Solna Pyramidvägen 3, 16 Sweden Sweden
Phone: (00 46) 8 - 80 90 00
Fax: (00 46) 8 - 80 72 06
Email Address: lars-olof.larsson@zeta.se

Comments: Pumps, Systems and Metering Systems for Oil and Gas
Company: Bran+Luebbe AS
Address: P.O.Box 453 1323 Hövik Norway, Sa Norway
Phone: (00 47) 67 – 83 26 50
Fax: (00 47) 67 – 83 26 51
Email Address: per.halck@processequipment.spx.com

Comments: Pumps, Systems, Analyzers and Metering Systems
Company: AXFLOW SAS
Address: 87 rue des Poiriers Parc Ste Apolline, BP 72 Plaisir Cedex 78372 France
Phone: (00 33) 1 - 30 68 41 41
Fax: (00 33) 1 - 30 68 41 00
Email Address: info@axflow.fr
Web Site: www.axflow.fr

Comments: Pumps, Systems, Analyzers and Metering Systems for Oil and Gas
Company: Bran + Luebbe S.L.
Address: c/ Antonio de Cabezón, No. 83 28034 Madrid Spain
Phone: (00 34) 91 – 657 40 40
Fax: (00 34) 91 – 662 33 50
?????: Phone (00 58) 212 – 235 02 16 / 239 73 20
?????: Fax (00 58) 212 – 235 91 68

Comments: none
Company: Bran + Luebbe
Address: Dipl.-Ing. Adam Szulc Rembielinskiego 1/2M42 09 400 Plock Poland
Phone: (00 48) 24 - 2 77 18 80
Fax: (00 48) 24 - 2 77 18 81
Email Address: adam_szulc@bran-luebbe.pl

Comments: Pumps and Systems
Company: BOCHAKO Chemie
Address: und Technik GmbH Lauenburger Str. 3-5 21493 Schwarzenbek, Ge Latvia (non-exclusive)
Phone: 04151-8699-0
Fax: 04151-8699-29

Comments: Analyzer (On-line Monitors only)
Company: PPA SLAVUTICH
Address: St. Predslavinskaya P.O.Box 422 Kyiv 150, 03150 Ukraine
Phone: 00380/44/536-02-29
Email Address: ppas@i.kiev.ua

Comments: Pumps, Systems, Analyzers and Metering Systems for Oil and Gas
Company: AxFlow Process Equipment B.V.
Address: De Steiger 24 1351 AB Almere Netherlands
Phone: (00 31) 36 - 53 81 211
Fax: (00 31) 36 - 53 14 004
Email Address: axflow@axflow.nl

Comments: Pumps, Systems, Analyzers and Metering Systems for Oil and Gas
Company: AxFlow S.p.A.
Address: Via del Commercio snc 20090 Buccinasco (MI) Italy
Phone: (00 39) 02 48 48 01
Fax: (00 39) 02 48 40 19 26
Email Address: xxxx.yyyy@axflow.it


View internet links for Bran+Luebbe >>>

Pulsafeeder

Pulsafeeder offers a wide array of pumps and control equipment to fit almost any application requirement.

Product(s) / Service(s): metering pumps
Source / Origin of Design: unknown
Contact Information:
area rep locator on web site
Web Site: View internet links for Pulsafeeder >>>

Teikoku USA / Chempump

Since 1963, Chem/Meter pumps have been providing metering pump users with highly accurate, responsive and sealless solutions to the industry's most demanding process and OEM applications. Designed in response the users' needs for a higher degree of reliability, Chem/Meter delivers these solutions in highly engineered or off-the-shelf packages that incorporate the latest in electronic automated flow control, leak detection and modular steady flow performance.

Product(s) / Service(s): Chem/Meter pumps
Source / Origin of Design: unknown
Contact Information:
959 Mearns Road
Warminster, PA 18974
Phone: 215-343-6000
Fax: 267-486-1037
View internet links for Teikoku USA / Chempump >>>

Dosatron

Water flow powered proportional dosing.

Product(s) / Service(s): metering / dosing pumps
Source / Origin of Design: unknown
Contact Information:
2090 Sunnydale Blvd.
Clearwater, FL 33765
View internet links for Dosatron >>>

Eldex Laboratories Inc.

Optos Series metering pumps can be used wherever precise flow rate control, particularly at high pressures, is required.  Optos pumps are well suited for process control, petrochemical, reactant feed, and a wide range of laboratory applications.

Product(s) / Service(s): Optos Series High Pressure Precision Metering Pumps
Source / Origin of Design: unknown
Contact Information:
30 Executive Court
Napa, CA  94558-6278
View internet links for Eldex Laboratories Inc. >>>

Zenith Pumps

Colfax pump group - helical gear metering.

Product(s) / Service(s): metering pumps
Source / Origin of Design: unknown
Contact Information:
contact form on web site
View internet links for Zenith Pumps >>>

ProMinent Fluid Controls, Inc.

Many types PLUS the high pressure "specials" from the old ORLITA range.

Product(s) / Service(s): metering pumps
Source / Origin of Design: unknown
Contact Information:
ProMinent Fluid Controls, Inc.
R.I.D.C. Park West
136 Industry Drive
Pittsburgh, PA 15275
View internet links for ProMinent Fluid Controls, Inc. >>>

S.R. Metering Pumps and Systems

Samir & R Tambat 7, Shashtrinagar Colony,Indiranagar, Nasik.- 422009.Indai

Product(s) / Service(s): metering / packed plunger pumps
Source / Origin of Design: unknown
Contact Information:
17, Shashtrinagar Colony,Indiranagar,
Nasik.- 422009.
View internet links for S.R. Metering Pumps and Systems >>>

Flowserve

reciprocating diaphragm head metering pumps

Product(s) / Service(s): metering pumps
Source / Origin of Design: was DURCO
Contact Information:
sales locator on website
View internet links for Flowserve >>>

Mahr Metering Systems

Mahr Metering Systems Corporation 1991 spin off from Feinpruef Corporation, Charlotte, NC previous specialty gear type metering pumps. Metering pumps are among the most crucial components of many manufacturing and research & development processes. We combine high-precision gear metering pumps with state-of-the-art automation to create systems that our customers can depend on 365 days a year. Every system built by Mahr is custom-made for its application.

Product(s) / Service(s): metering pumps
Source / Origin of Design: unknown
Contact Information:
Mahr Metering Systems Corporation
1415-A Cross Beam Dr.
Charlotte, NC 28217
ph. 704.525.7128
fx. 704.525.8290
View internet links for Mahr Metering Systems >>>

Finemech

Precision mechanical components; Name is derived from Feinmechanik, the German remote control micro meters.

Product(s) / Service(s): DOCSA Micro Metering Pumps with remotable controllers
Source / Origin of Design: unknown
Contact Information:
Finemech Inc.
35 Kiowa Court
Portola Valley
CA 94028
View internet links for Finemech >>>

Valcor

The Valcor solenoid operated metering pumps are a positive displacement devices in which the effects of fluid pressure, density and viscosity are minimized, because the flow rate is almost entirely dependent on the volume displaced by the piston during each stroke and on the number of strokes per unit time.

Product(s) / Service(s): dispensing / metering pumps
Source / Origin of Design: unknown
Contact Information:
Valcor Engineering Corporation
2 Lawrence Road
Springfield, NJ 07081
View internet links for Valcor >>>

Gorman-Rupp Industries

Gorman-Rupp , bellows displacement chambers.

Product(s) / Service(s): bellows metering pumps
Source / Origin of Design: unknown
Contact Information:
180 Hines Ave., Bellville, OH 44813
View internet links for Gorman-Rupp Industries >>>

Madden Manufacturing Inc

Madden diaphragm metering pumps are designed for tough industrial jobs where chemicals must be pumped 24 hours a day, 365 days a year. Engineered materials are used for the wetted end to pump virtually any chemical, from acids to caustics. Even viscous liquids and suspended solids can be pumped with volume controlled accuracy.

Product(s) / Service(s): diaphragm metering pumps
Source / Origin of Design: unknown
P.O. Box 387
Elkhart, IN 46515
1.800.369.6233
Phone: 574.295.4292
Fax: 574.295.7562
View internet links for Madden Manufacturing Inc >>>

Signal Metering Pumps

With the most universal range of dosing/metering pumps in the UK, Signal is dedicated to providing you with a total partnership in pumps – and the innovation that comes from new, more intelligent solutions.

Product(s) / Service(s): Solenoid, Plunger, Mechanical diaphragm, Hydraulic, diaphragm/double diaphragm, Pneumatic, signal range of metering pumps
Source / Origin of Design: unknown
Contact Information:
Signal Metering Pumps
Gee House
Holborn Hill
Birmingham B7 5JR
T 0121 326 1745
F 0121 326 1779
View internet links for Signal Metering Pumps >>>

Hydra-Cell

Wanner International Ltd. UK. Compact, cost-effective pump systems for high-performance metering applications .

Product(s) / Service(s): Hydra-Cell Metering Pumps
Source / Origin of Design: unknown
Contact Information:
Wanner International Ltd.
Units 8 and 9 Fleet Business Park
Sandy lane, Church Crookham
Hampshire GU52 8BF England
Tel: +44- 01252-816847
View internet links for Hydra-Cell >>>

Netzsch

Mini Metering Pumps are available as bareshaft or complete with constant or variable speed drives. Standard Mini Pumps are manufactured with 316 stainless steel wetted components and single mechanical seal, with various stator elastomers available.

Product(s) / Service(s): NEMO® Mini Metering Series
Source / Origin of Design: unknown
Contact Information:
NEMO® Pump Division: Contacts available via web site
View internet links for Netzsch >>>

IVEK Corporation

IVEK offers a 316 stainless steel, sanitary split case rotary Pump Module to complement its line of precision, positive displacement liquid dispensing systems. Its superior design allows easy access to all wetted components for thorough cleaning and sterilization, as well as interchangeability of ceramic pump sets (B, C, D and 16mm). The ceramic piston/cylinder set can be removed and replaced without losing a preset calibration position. This eliminates manual recalibration, which is time consuming and in some applications material cost-prohibitive. The Split Case (Macro Rotary) Pump Module is designed for use with IVEK’s Heavy Duty Motor/Base Modules.

Product(s) / Service(s): Precision Liquid Dispensing, Metering & Ceramic Pumps
Source / Origin of Design: unknown
Contact Information:
IVEK Corporation
10 Fairbanks Rd
North Springfield, VT 05150 USA
View internet links for IVEK Corporation >>>

Lutz-Jesco America

Simplex and duplex models are available. The rugged design makes this pump ideal for most municipal or industrial water treatment chemical pplications. This pump has a metering head designed with a separation chamber behind the diaphragm which will protect the body of the pump should the diaphragm rupture or crack due to wear.

Product(s) / Service(s): metering pumps
Source / Origin of Design: unknown
Contact Information:
Lutz-JESCO America Corp.
55 Bermar Park
Rochester, New York 14624 USA
View internet links for Lutz-Jesco America >>>

Inductive Pump

Patented state of the art technology in magnetically driven metering pumps.

Product(s) / Service(s): magnetically driven metering pumps
Source / Origin of Design: unknown
Contact Information:
2338 Broad Street
Frankfort, NY 13340
Phone: 315-732-6661
Toll Free: 1-866-732-3049
Fax: 315-732-6669
View internet links for Inductive Pump >>>

Sidewinder Pumps

Sidewinder Pumps manufacturers pneumatic chemical metering pumps and electric chemical metering pumps in Lafayette, Louisiana, USA. Designed for high-pressure chemical injection and low-pressure chemical dosing applications.

Product(s) / Service(s): metering pumps
Source / Origin of Design: unknown
Contact Information:
PO Box 80769
Lafayette, LA 70598
View internet links for Sidewinder Pumps >>>

LMI Milton Roy

AKA Liquid Metering Instruments Electronic dosing, div Milton Roy, low pressure.

Product(s) / Service(s): LMI Electronic Chemical Metering Pumps
Source / Origin of Design: unknown
Contact Information:
LMI, 201 Ivyland Road
Ivyland, PA 18974
(tel) 215-293-0401
(fax) 215-293-0445
View internet links for LMI Milton Roy >>>

Neptune

NEPTUNE CHEMICAL PUMP COMPANY INC was "RA Industries". Neptune Hydraulic Diaphragm metering pumps are typically used for chemical metering in process and agricultural industries. Chemical metering pumps are avavilable for high and low pressure applications with manual and electronic stroke control.

Product(s) / Service(s): metering pumps
Source / Origin of Design: unknown
Contact Information:
P.O. Box 247
Lansdale, PA 19446-0247
View internet links for Neptune >>>

Jaeco Fluid Systems

All Jaeco motor driven pumps have a steady-state accuracy of ± .5%. Liquid ends are available in a variety of materials to meet a broad spectrum of chemical requirements. Both simplex and duplex models offer a wide range of capacities and pressure ratings. Most configurations and liquid end components are available from stock so assembled pumps can be shipped within 48 hours.

Product(s) / Service(s): Plunger, diaphragm, & electronic metering pumps.
Source / Origin of Design: unknown
Contact Information:
17 Lee Blvd. Ste. D
Malvern, PA 19355-1234
Toll Free: 1-877-778-3456
Phone: 610-407-7207
Fax: 610-407-7211
View internet links for Jaeco Fluid Systems >>>

Kelair

Kelair Pumps specialises in industrial pumps for the mining, chemical, pharmaceutical, petrochemical, food and beverage industries, and industry in general. Kelair further specialises in steam turbines, metering packages for chemical dosing.

Product(s) / Service(s): pumps for the mining, chemical, pharmaceutical, petrochemical, food and beverage industries
Source / Origin of Design: Unknown
Contact Information:
Not Available
View internet links for Kelair >>>

Williams

Williams the Company has been recognized as one of the leading manufacturers of pneumatic metering pumps and chemical injection systems.

Product(s) / Service(s): pneumatic metering pumps and chemical injection systems
Source / Origin of Design: Unknown
Contact Information:
Not Available
View internet links for Williams >>>

LMI - Milton Roy

LMI - Milton Roy Liquid Metronics Incorporated (LMI) is the leading manufacturer of Chemical Metering Pumps, Controllers, and accessories.

Product(s) / Service(s): Chemical Metering Pumps, Controllers, and accessories
Source / Origin of Design: Unknown
Contact Information:
Not Available
View internet links for LMI - Milton Roy >>>

Pompe Cucchi

Pompe Cucchi is present by over 40 years in the pumping metering and transfering fluids sector. We produce our pumps using numerically controlled machining centre so to guarantee an high quality level and interchangeability.

Product(s) / Service(s): pumping metering and transfering fluids
Source / Origin of Design: Unknown
Contact Information:
Not Available
View internet links for Pompe Cucchi >>>


Wikipedia Dosing Pump

Dosing generally applies to feeding chemicals or medicines in small quantities into a process fluid or to a living being at intervals or to atmosphere at intervals to give sufficient time for the chemical or medicine to react or show the results. This word dosing as per the dictionary is the verb format for the word dose which is a noun.
In the case of human beings or animals (i.e. living beings) the word dose is generally used but in the case of inanimate objects the word dosing is being used. This is only in practice.

The word dosing is very commonly used by engineers in Thermal power stations or in any industry where steam is being generated. Dosing procedures are also in vogue in textile and similar industries where chemical treatment is involved. In a power station treatment chemicals are injected or fed to boiler and also to feed and make up water under pressure, but in small dosages or rate of injection. The feeding at all places is done by means of small capacity dosing pumps specially designed for the duty demanded.

The feeding of chemicals in agriculture has also become common due to technology developments in this field. However the dosing in the agricultural field is done by means of hand held pressure spray pumps or similar devices.
Some times aerial spraying of chemicals by fixed quantities at intervals or dosing is also adopted for agricultural spraying or for atmospheric spraying for eliminating certain types of harmful insects.


Wikipedia Metering Pump

A Metering pump is a pump used to pump liquids at adjustable flow rates which are precise when averaged over time. Delivery of fluids in precise adjustable flow rates is sometimes called metering. The term "metering pump" is based on the application or use rather than the exact kind of pump used, although a couple types of pumps are far more suitable than most other types of pumps.

Although metering pumps can pump water, they are often used to pump chemicals, solutions, or other liquids. Many metering pumps are rated to be able to pump into a high discharge pressure. They are typically made to meter at flow rates which are practically constant (when averaged over time) within a wide range of discharge (outlet) pressure. Manufacturers provide each of their models of metering pumps with a maximum discharge pressure rating against which each model is guaranteed to be able to pump against. An engineer, designer, or user should ensure that the pressure and temperature ratings and wetted pump materials are compatible for the application and the type of liquid being pumped.

Most metering pumps have a pump head and a motor. The liquid being pumped goes through the pump head, entering through an inlet line and leaving through an outlet line. The motor is commonly an electric motor which drives the pump head.
Many metering pumps are piston-driven. Piston pumps are positive displacement pumps which can be designed to pump at practically constant flow rates (averaged over time) against a wide range of discharge pressure, including high discharge pressures of thousands of psi.

Piston-driven metering pumps commonly work as follows: There is a piston (sometimes called plunger), typically cylindrical, which can go in and out of a correspondingly shaped chamber in the pump head. The inlet and outlet lines are joined to the piston chamber. There are two check valves, often ball check valves, attached to the pump head, one at the inlet line and the other at the outlet line. The inlet valve allows flow from the inlet line to the piston chamber, but not in the reverse direction. The outlet valve allows flow from the chamber to the outlet line, but not in reverse. The motor repeatedly moves the piston into and out of the piston chamber, causing the volume of the chamber to repeatedly become smaller and larger. When the piston moves out, a vacuum is created. Low pressure in the chamber causes liquid to enter and fill the chamber through the inlet check valve, but higher pressure at the outlet causes the outlet valve to shut. Then when the piston moves in, it pressurizes the liquid in the chamber. High pressure in the chamber causes the inlet valve to shut and forces the outlet valve to open, forcing liquid out at the outlet. These alternating suction and discharge strokes are repeated over and over to meter the liquid. In back of the chamber, there is packing around the piston or a doughnut-shaped seal with a toroid-shaped sphincter-like spring inside compressing the seal around the piston. This holds the fluid pressure when the piston slides in and out and makes the pump leak-tight. The packing or seals can wear out after prolonged use and can be replaced. The metering rate can be adjusted by varying the strokelength by which the piston moves back and forth or varying the speed of the piston motion.

A single-piston pump delivers liquid to the outlet only during the discharge stroke. If the piston's suction and discharge strokes occur at the same speed and liquid is metered out half the time the pump is working, then the overall metering rate averaged over time equals half the average flow rate during the discharge stroke. Some single-piston pumps may have a constant slow piston motion for discharge and a quick retract motion for refilling the pump head. In such cases, the overall metering rate is practically equal to the pumping rate during the discharge stroke.
Pumps used in high pressure chromatography such as HPLC and ion chromatography are much like small piston metering pumps. For wear resistance and chemical resistance to solvents, etc., typically the pistons are made of artificial sapphire and the ball check valves have ruby balls and sapphire seats. To produce good chromatograms, it is desirable to have a pumping flow rate as constant as possible. Either a single piston pump with a quick refill is used or a double pump head with coordinated piston strokes is used to provide as constant a pumping rate as possible.
In order to avoid leakage at the packing or seal particularly when a liquid is dangerous, toxic, or noxious, diaphragm pumps are used for metering. Diaphragm pumps have a diaphragm through which repeated compression/decompression motion is transmitted. The liquid does not penetrate through the diaphragm, so the liquid inside the pump is sealed off from the outside. Such motion changes the volume of a chamber in the pump head so that liquid enters through an inlet check valve during decompression and exits through an outlet check valve during compression, in a manner similar to piston pumps. Diaphragm pumps can also be made which discharge at fairly high pressure. Diaphragm metering pumps are commonly hydraulically driven.

Peristaltic pumps use motor-driven rollers to roll along flexible tubing, compressing it to push forward a liquid inside. Although peristaltic pumps can be used to meter at lower pressures, the flexible tubing is limited in the level of pressure it can withstand.

The maximum pressure rating of a metering pump is actually the top of the discharge pressure range the pump is guaranteed to pump against at a reasonably controllable flow rate. The pump itself is a pressurizing device often capable of exceeding its pressure rating, although not guaranteed to. For this reason, if there is any stop valve downstream of the pump, a pressure relief valve should be placed in between to prevent overpressuring of the tubing or piping line in case the stop valve is inadvertently shut while the pump is running. The relief valve setting should be below the maximum pressure rating that the piping, tubing, or any other components there could withstand.

Liquids are only very slightly compressible. This property of liquids lets metering pumps discharge liquids at high pressure. Since a liquid can be only slightly compressed during a discharge stroke, it is forced out of the pump head. Gases are much more compressible. Metering pumps are not good at pumping gases. Sometimes, a metering or similar pump has to be primed before operation, i. e. the pump head filled with the liquid to be pumped. When gas bubbles enter a pump head, the compression motion compresses the gas but has a hard time forcing it out of the pump head. The pump may stop pumping liquid with gas bubbles in the pump head even though mechanically the pump is going through the motions, repeatedly compressing and decompressing the bubbles. To prevent this type of "vapor lock", chromatography solvents are often degassed before pumping.

If the pressure at the outlet is lower than the pressure at the inlet and remains that way in spite of the pumping, then this pressure difference opens both check valves simultaneously and the liquid flows through the pump head uncontrollably from inlet to outlet. This can happen whether the pump is working or not. This situation can avoided by placing a correctly-rated positive pressure differential check valve downstream of the pump. Such a valve will only open if a minimum rated pressure differential across the valve is exceeded, something which most high pressure metering pumps can easily exceed.
Dosing / Metering Pump



Fluid Flow Control
Greg St. Industrial Center, UK SK5 7BS EU
For insertions or changes contact the editor; For technical updates contact Dr. A. V. Ghavrish – Engineer.
Email:
Pulsating-Equipment@Fluid-Flow-Control.com


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