The Metering pumps are positive displacement chemical dosing devices that may be adjusted manually or automatically depending on the process conditions. It is capable of pumping a wide range of chemicals, including acids, bases, corrosives, viscous liquids, and slurries, with a high level of repeated precision. A metering pump delivers a precise volumetric flow rate by transporting a certain amount of liquid over a given period of time. The supply of fluids at precise, predictable flow rates is referred to as metering. Despite the fact that a few types of pumps are far more suited than most others, the term “Metering pump” relates to the application or purpose rather than the specific type of pump used.
A reciprocating piston generates the pumping action, which is either in direct contact with the process fluid or insulated from it by a diaphragm. Hydraulic fluid is used to move the diaphragm between the piston and the diaphragm. Metering pumps are commonly employed in applications that have one or more of the following characteristics. Metering pumps transport a specific amount of liquid in a predetermined amount of time, resulting in an exact volumetric flow rate.
Metering is the delivery of fluids at exact, controllable flow rates. Although a few types of pumps are significantly more suited than most other types of pumps, the phrase “Metering pumps” refers to the application or purpose rather than the specific type of pump employed.
Metering pumps may pump water, but they’re more commonly employed to transport chemicals, solutions, or other liquids. Many metering pumps are designed to operate at high discharge pressures. They’re usually designed to measure flow rates that are almost constant (when averaged over time) throughout a wide range of discharge (outlet) pressures.
The pressure and temperature ratings, as well as the wetted pump materials, should be suitable for the application and the type of liquid being pushed, according to an engineer, designer, or user. A pump head and a motor are found on most metering pumps. The liquid being pumped enters through an inlet line and exits through an output line in the pump head. The motor that powers the pump head is usually an electric motor.
COMPONENT OF METERING PUMPS
A constant-speed AC motor is commonly used to power the metering pumps. Drivers with variable speeds, pneumatics, and hydraulics are also used. The service circumstances and type of the fluid to be handled influence the liquid end design and materials of construction. Temperature, flow rate, fluid viscosity, corrosivity, and other variables are all taken into account.
The drive mechanism converts the driver’s rotating motion into reciprocating motion. To ensure reliability during continuous operation, industrial duty pumps would submerge this section of the pump in an oil bath. Changing the stroke length, effective stroke length, or stroking speed can change the pump flow rate. A micrometer screw adjustment is included with most metering pumps.
LIQUID END
The service circumstances and the type of fluid to be handled influence the liquid end design and materials of construction. Temperature, flow rate, fluid viscosity, corrosivity, and other variables are all taken into account.
DRIVER MECHANISM
The driver’s rotating motion is translated into reciprocating action via the drive mechanism. To ensure reliability during continuous operation, industrial duty pumps would submerge this section of the pump in an oil bath.
FLOWING ADJUSTMENT
The pump flow rate can be adjusted by changing the stroke length, effective stroke length, or stroking speed. A micrometer screw adjustment, similar to the one seen above, is included with most metering pumps. To alter the pump flow rate in response to a process indication, the micrometer can be replaced with an electronic or pneumatic actuator.
RELIEF VALVES FOR SAFETY
To safeguard the pipe from over-pressure, most piping systems need the installation of an external safety valve. Internal safety valves are built into diaphragm pumps to safeguard them, however, external safety valves are still suggested. The working pressures of the pumps should be matched by the safety relief valves. Specialty steel, 316SS, alloy 20, and PVC are common valve materials.
VALVES FOR BACK PRESSURE
A Metering pump system requires a higher discharge pressure than the suction or intake line to prevent unmetered liquid from flowing freely through the pump. A back pressure valve is necessary when the process does not deliver a minimum of 25 psi above the suction pressure. Specialty steel, 316SS, alloy 20, and PVC are common valve materials.
PULSATION DAMPENERS
The reciprocating action of the metering pumps creates a pulsing discharge flow. A pulsation dampener may remove over 90% of the pulsations in applications that need constant flow. For pressures up to 1000 psi, standard dampeners are available. The cubic inch/stroke displacement of the given pump is used to size it.
COLUMNS FOR CALIBRATION
Metering pumps should be thoroughly inspected by the manufacturer. Pump calibration should be checked on a regular basis after installation to ensure correct functioning, especially after any maintenance. Calibration columns can be a cost-effective way to ensure pumping precision.
SLUDGE TRAPS
Installing a strainer in the suction pipe of metering pumps will protect the check valves from particles and trash. A sludge trap is necessary when pumping concentrated sulfuric acid to catch sludge particles while allowing for easy cleaning or flushing. For applications that pump fluid from replacement drums, foot valves, and strainers can be employed. Inline protection in systems is occasionally provided by “Y” type strainers.
DOSING SYSTEMS FOR CHEMICALS
A typical pre-engineered chemical dosing system includes manual control and all necessary accessories for proper operation. Other systems can employ a line of instruments to offer a complete closed-loop solution, or they can pace the dosage from a single input.
METERING PUMPS CHARACTERISTICS
A reciprocating piston creates the pumping motion. This reciprocating action creates a flow that may be seen as a sine wave. Unlike centrifugal pumps, the flow rate is unaffected by discharge pressure fluctuations. The characteristic curve of a metering pump flow vs. stroke is linear; however, it is not always proportional, since a 50 percent stroke setting may not equal 50 percent flow.
This is because the calibration line may not cross through 0 on both axes at the same time. Other flow rates versus stroke can be correctly predicted by measuring flow at two-stroke settings, graphing both locations, and drawing a straight line between them. Properly installed industrial-grade metering pumps have a steady-state accuracy of +/- 1.0 percent or greater.
A Metering pump accuracy is assessed across a range set by the pump’s turndown ratio, which may be modified to pump at any flow rate between 0 and its maximum capacity. The turndown ratio of most metering pumps is 10:1, which essentially indicates that the pump is within its accuracy rating anywhere between 10% and 100% of capacity. Centric is an example of a new-generation metering pump that has a 100:1 turndown ratio and higher accuracy. As a result, this design can correctly administer anywhere between 1% and 100% of capacity.
LIQUID END DESIGNS
The liquid end of the pump, also known as the wetted section, is chosen to fulfill the application’s unique service conditions. The required flow and pressure ratings, as well as the physical and chemical qualities of the liquid, are all taken into account. When dealing with dangerous or hazardous compounds, the capacity of the liquid end to safeguard the environment is also a crucial factor.
Several characteristics are shared by all liquid endings. The liquid is first sucked into the wetted end by a piston’s backward motion, then ejected by the forward motion. Check valves are installed at the suction and discharge connection locations of the metering pumps to achieve this. The chemical is contained and released by the check valves based on the system.
PLUNGER PACKED
The only liquid end in which the piston is in direct touch with the process fluid is the packed plunger-style liquid end. Excellent suction and discharge pressure capabilities; high-temperature resistance; and lowest NPSH needs are just a few of the benefits of direct contact. The wetted components of the reciprocating piston require packing to keep them sealed from the environment. This basic design is functional, although it restricts the usage of packed plunger pumps in some situations. This type of liquid end should not be used with dangerous or poisonous substances since a tiny amount of controlled leakage through the packing is to be expected.
OUR PRINCIPAL
Kiron Hydraulic Needs Private Limited, in collaboration with CHEONSEI PUMPS, offers a full metering pump solution. Cheonsei metering pumps are built with certain strengths in mind Whether you want energy efficiency, reduced maintenance costs, or a diaphragm with an extraordinarily long service life, we can help. Perhaps you need a metering pump that can handle supercritical fluids and liquid gas or one that can fulfill the most stringent criteria and demands in the oil and gas, chemical, cosmetics, pharmaceutical, biotechnology, or food and beverage industries.