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Pump Systems, Lubrication, Controls & Service FAQs
This section provides technical answers to common questions related to industrial pumps, vacuum systems, lubrication, controls, and pump repair. It is designed to support maintenance, reliability, and operations teams with practical guidance on system performance, troubleshooting, and best practices.
Liquid Pumps (Centrifugal and Positive Displacement)
What is the difference between a centrifugal pump and a positive displacement pump?
Centrifugal pumps use an impeller to convert rotational energy into fluid velocity and pressure, making them ideal for high-flow, low-viscosity applications. Positive displacement pumps move a fixed volume of fluid per cycle and are better suited for viscous fluids or precise flow control.
What causes pump cavitation?
Pump cavitation occurs when suction pressure drops below the liquid’s vapor pressure, forming vapor bubbles that collapse inside the impeller. This causes noise, vibration, and long-term damage.
How do I calculate Net Positive Suction Head (NPSH)?
The Net Positive Suction Head Available (NPSHa) is determined by the design of the piping system.
What are the signs of a failing mechanical seal?
Common signs include visible leakage near the shaft, spraying, unusual noise, or increased seal temperature.
When should a submersible pump be used instead of a surface pump?
Submersible pumps are recommended when suction lift exceeds approximately 25 feet or when quiet operation and limited space are required.
What does deadheading a pump mean?
Deadheading occurs when a pump runs against a closed discharge valve, causing rapid heat buildup that can damage seals and internal components.
How does fluid viscosity affect pump performance?
Higher viscosity increases power demand and reduces flow in centrifugal pumps. Positive displacement pumps handle viscous fluids more effectively.
What pump types are best for abrasive slurries?
Progressive cavity pumps and heavy-duty centrifugal pumps with hardened materials or wear liners are commonly used for abrasive applications.
What is the Best Efficiency Point (BEP)?
The Best Efficiency Point is the operating flow where a pump runs most efficiently with minimal vibration and wear.
Can a centrifugal pump run dry?
No. Most centrifugal pumps require liquid for seal lubrication and cooling.
What is priming?
Priming is the process of removing air from the pump casing and suction line to allow proper fluid flow.
How do magnetic drive pumps prevent leaks?
Magnetic drive pumps eliminate mechanical seals by using a magnetic coupling to drive the impeller, reducing leak risk.
What is the function of a pump volute?
The volute converts velocity energy into pressure energy.
Vacuum Pumps
How does a liquid ring vacuum pump work?
A liquid ring vacuum pump uses a rotating liquid seal to create compression chambers that evacuate gas.
What is the difference between rough vacuum and high vacuum?
Rough vacuum refers to pressures above 1 Torr, while high vacuum typically begins below 10⁻³ Torr.
Why is oil mist coming from the vacuum pump exhaust?
This usually indicates a saturated or damaged oil mist eliminator filter.
Can standard motor oil be used in a vacuum pump?
No. Vacuum pump oil has a low vapor pressure designed specifically for vacuum applications.
What is a blank-off test?
A blank-off test measures the pump’s ultimate vacuum by sealing the inlet.
How often should vacuum pump oil be changed?
Typically every 500 to 1,000 operating hours or sooner if contaminated.
What causes a vacuum pump to overheat?
High ambient temperature, low oil levels, or operating at high pressure for extended periods.
What is a gas ballast?
A gas ballast allows controlled air entry to prevent vapor condensation inside the pump oil.
What is a dry screw vacuum pump?
A dry screw vacuum pump uses intermeshing screws to move gas without oil in the compression chamber.
Oils, Greases, and Lubrication
What is the difference between oil and grease?
Grease is oil combined with a thickener that allows it to remain in place.
What is viscosity index?
Viscosity index measures how much an oil’s viscosity changes with temperature.
Can different greases be mixed?
Generally no. Incompatible thickeners can cause grease failure.
What is NLGI consistency?
The NLGI scale rates grease firmness from 000 to 6, with #2 being most common for industrial use.
What are the benefits of synthetic lubricants?
They provide better temperature stability, longer service life, and improved film strength.
What is boundary lubrication?
A condition where the lubricant film is too thin to prevent metal-to-metal contact.
Why does grease turn black?
Typically due to oxidation, high heat, or metal wear contamination.
How much grease should be added to a bearing?
Most bearings should be filled with only 30 to 50 percent of free space.
What is an extreme pressure additive?
An EP additive forms a protective layer under high loads.
How does water contamination affect oil?
It causes corrosion, oxidation, and reduced lubricating performance.
Systems and Controls
What is a Variable Frequency Drive (VFD)?
A VFD controls motor speed by adjusting electrical frequency to improve efficiency.
What is a SCADA system?
SCADA systems monitor and control pump operations remotely.
How does a pressure transducer work?
It converts pressure into an electrical signal for controllers.
What is a PID loop?
A control algorithm that maintains stable pressure or flow.
Why use a soft starter?
To reduce electrical inrush current and mechanical shock.
What is a check valve used for?
To prevent reverse flow when a pump shuts down.
What is a PLC?
A programmable logic controller executes system logic based on sensor inputs.
What is water hammer?
A pressure surge caused by sudden fluid flow changes.
How do VFDs reduce water hammer?
By providing gradual acceleration and deceleration.
What is a lead-lag pump system?
A configuration where pumps alternate operation to balance wear.
What is a float switch?
A device that detects liquid level.
What does dry-run protection do?
It shuts the pump down if flow or prime is lost.
How do I monitor pump vibration?
Using vibration sensors or accelerometers.
What is phase-loss protection?
A safety feature that shuts down motors if a power phase fails.
What is the difference between an HMI and a PLC?
The PLC performs logic; the HMI displays system data.
Repair and Service
Why is my pump vibrating excessively?
Common causes include misalignment, worn bearings, imbalance, or hydraulic issues.
How often should pumps be laser aligned?
During installation and after major maintenance.
What is lapping a seal face?
A precision process to ensure perfectly flat sealing surfaces.
How do I troubleshoot a pump that will not start?
Check power supply, fuses, motor windings, and shaft rotation.
What is a pump audit?
An evaluation of system performance, energy use, and reliability.
Can cracked pump casings be repaired?
Sometimes, but replacement is often safer for high-pressure service.
Why are bearings failing prematurely?
Often due to contamination, improper lubrication, or misalignment.
How do I test a motor for grounding?
Using a megohmmeter to check insulation resistance.
What is proactive maintenance?
Maintenance performed to prevent failures rather than react to them.
How do I pack a stuffing box?
Install rings with staggered joints and tighten gradually.
What is dynamic balancing?
Balancing rotating components while spinning.
How do I detect vacuum leaks?
Using helium leak detection or ultrasonic testing.
Should I repair or replace my pump?
If repair exceeds 50–60 percent of replacement cost, replacement is usually recommended.
Common Troubleshooting Questions
Why is my pump noisy?
Noise may indicate cavitation, bearing wear, or loose mounting.
Why is discharge pressure low?
Possible causes include wear, low speed, or suction restriction.
Why is the motor drawing high current?
High viscosity, mechanical binding, or oversized impeller.
Why did my pump lose prime?
Likely due to suction leaks or foot valve failure.
Why is the mechanical seal leaking?
Often caused by dry running or improper installation.
Why is my vacuum pump smoking?
Usually oil contamination or exhaust filter issues.
What causes pump shafts to break?
Fatigue from misalignment or hydraulic shock.
Why is my VFD tripping on overvoltage?
Typically caused by regenerative energy during rapid deceleration.
Why is liquid foamy?
Usually air entrainment or suction leaks.
How hot is too hot for bearings?
Temperatures above 180°F indicate a problem.
What is hunting in a control system?
Continuous oscillation caused by improper tuning.
Why is the motor running hot?
Low voltage, high ambient temperature, or cooling obstruction.
What does milky oil indicate?
Water contamination.
Why is discharge surging?
Often due to suction blockage or operation off the pump curve.
Why should pump repair be performed by professionals?
Professional repair ensures precision alignment, balancing, and OEM-level tolerances.
Glossary
A
Absolute Pressure: The total pressure within a system, measured relative to a perfect vacuum.
Absolute Zero: The lowest possible temperature, 0 Kelvin (-273.15°C), where all molecular motion ceases.
Accumulator: A device that stores fluid under pressure for future use in a hydraulic system.
ACFM (Actual Cubic Feet per Minute): The actual volume of gas pumped per minute, measured at the inlet conditions.
Actuator: A device that moves or controls a valve, often powered by air, electricity, or hydraulics.
Adsorbate: A material that takes in gas by adsorption.
Adsorption: The process by which gas molecules adhere to the surface of a solid.
Air Chamber: A chamber filled with air to absorb pressure fluctuations in a pump system.
Air Separator: A device that removes air from the fluid before it enters the pump.
Air-Inlet Valve: A valve used to allow atmospheric air into a vacuum system, also known as a vacuum breaker or vent valve.
Airlock: A condition where air is trapped in the pump or piping system, preventing normal fluid flow.
AIS – American Iron and Steel
Angle Valve: A valve with an inlet and outlet at a 90-degree angle, used to change the direction of flow.
ANSI Pump: A pump that meets the standards set by the American National Standards Institute (ANSI) for chemical process pumps.
ANSI/ASME B73.1: A standard for horizontal end suction centrifugal pumps used in chemical process industries.
Antisuckback Valve: A device that prevents the backflow of oil and air from a vacuum pump into the system when the pump stops.
Atmospheric Pressure: The pressure exerted by the weight of the atmosphere, typically measured as 760 mmHg at sea level.
Axial Flow Pump: A type of pump where the fluid flows parallel to the pump shaft.
Axial Thrust: The force exerted along the axis of the pump shaft, which can affect bearing life and pump performance.
B
BABA – Build American Buy American
Back Pull-Out Design: A pump design that allows the removal of the rotating element without disturbing the piping connections.
Backflow: The reverse flow of fluid in a piping system, which can cause damage or contamination.
Backing Pump: A pump used to maintain the pressure in the foreline of a high-vacuum pump.
Backstreaming: The flow of pump oil or other working fluid back into the vacuum system.
Baffle: A device used to direct or control the flow of fluid within a pump or piping system.
Balance Line: A line that connects the high-pressure side of a pump to the low-pressure side to balance hydraulic forces.
Ball Valve: A valve that uses a spherical ball with a hole through it to control flow, offering quick shutoff.
Base Pressure: The lowest pressure that a vacuum system can achieve without any gas load.
Baseplate: A metal plate on which the pump and motor are mounted to ensure alignment and stability.
Bearing: A component that supports the rotating shaft and reduces friction.
Bellows Pump: A type of positive displacement pump that uses a bellows mechanism to move fluid.
Bellows Seal: A type of mechanical seal that uses a flexible bellows to accommodate shaft movement.
Belt-Drive Pump: A pump driven by a belt connected to a motor, allowing for variable pump speeds.
Bleed Valve: A valve used to remove air or gas from a pump or piping system.
Booster Pump: A pump used to increase the capacity and efficiency of a primary vacuum pump.
Booster Pump: A pump used to increase the pressure of a fluid in a system.
Bubble Point: The pressure at which gas bubbles start to form in a liquid, important for avoiding cavitation.
Butterfly Valve: A valve with a rotating disc to regulate flow, commonly used for large pipe diameters.
Bypass Valve: A valve that allows fluid to flow around a pump or other component to control pressure or flow rate.
C
Canned Motor Pump: A pump with a motor enclosed in a hermetically sealed can, eliminating the need for a mechanical seal.
Capture Pump: A type of vacuum pump that removes gas molecules by trapping them on a surface.
Cartridge Pump: A pump design where the entire pumping element can be removed as a single unit for maintenance.
Cartridge Seal: A pre-assembled mechanical seal unit that can be easily installed or replaced.
Casing Wear Ring: A replaceable ring in the pump casing that reduces leakage and wear.
Cavitation: The formation and collapse of vapor bubbles in a fluid, which can cause damage to the pump.
Centrifugal Pump: A type of pump that uses a rotating impeller to increase the velocity of a fluid, converting kinetic energy into pressure energy.
Check Valve: A valve that allows fluid to flow in one direction only, preventing backflow.
Closed Impeller: An impeller with shrouds on both sides to reduce leakage and improve efficiency.
Closed-Coupled Motor: A motor directly connected to the pump without a separate coupling, often used in small pumps.
Closed-Coupled Pump: A pump where the impeller is directly mounted on the motor shaft, eliminating the need for a separate coupling.
Cold Trap: A device used to condense vapors from a vacuum system by cooling them, preventing contamination of the pump.
Compound Mechanical Pump: A pump with multiple stages of compression to achieve higher vacuum levels.
Compression Ratio: The ratio of the outlet pressure to the inlet pressure of a pump for a specific gas.
Conductance: The measure of the capacity of a vacuum system’s piping to allow gas flow, typically measured in liters per second.
Control Valve: A valve used to regulate flow, pressure, or temperature in a system, often operated by an actuator.
Critical Flow: The flow rate at which a pump operates most efficiently, often indicated on the pump curve.
Critical Speed: The speed at which a pump’s rotating components resonate, potentially causing damage.
Cryogenic Pump: A pump designed to handle extremely low-temperature fluids, such as liquid nitrogen or liquid oxygen.
Cryopump: A vacuum pump that uses cold surfaces to condense and trap gases.
Cutwater: The point in a pump volute where the fluid is directed towards the discharge.
D
Degassing Valve: A valve used to remove dissolved gases from a fluid before it enters the pump.
Degassing: The removal of gas and vapors from a substance under vacuum.
Diaphragm Pump: A type of positive displacement pump that uses a diaphragm to move fluid.
Diaphragm Valve: A valve that uses a flexible diaphragm to control flow, suitable for corrosive or viscous fluids.
Diffuser: A component that slows down the fluid flow and increases pressure in a centrifugal pump.
Diffusion Pump: A high-vacuum pump that uses a jet of vapor to direct gas molecules towards the pump outlet.
Direct-Drive Pump: A pump with a motor directly coupled to the pump rotor, providing a fixed pump speed.
Discharge Head: The vertical distance between the pump’s centerline and the point of fluid discharge.
Displacement: The geometric volume swept by the pump mechanism per unit time, also known as free air displacement.
Double Mechanical Seal: A mechanical seal arrangement with two seals in series or parallel to provide additional leakage protection.
Double Suction Pump: A centrifugal pump with two suction inlets, designed to balance the hydraulic forces.
Dry Pump: A vacuum pump that operates without any lubricating or sealing fluids.
Dry Running: Operating a pump without fluid, which can cause damage to the pump components.
Dynamic Head: It is the total head that a pump must overcome, including static head and friction losses.
E
Efficiency: The ratio of the pump’s hydraulic power output to the mechanical power input, expressed as a percentage.
Elastomer: A rubber-like material used in seals and gaskets for flexibility and durability.
Elastomeric Coupling: A flexible coupling made of elastomeric material to absorb shock and vibration.
End Suction Pump: A type of centrifugal pump with the suction inlet on one end and the discharge outlet on the top.
End-of-Curve: The point on a pump’s performance curve where it operates at maximum flow and minimum head.
End-of-Life: The point at which a pump or its components are no longer functional or efficient and need replacement.
Exhaust Pressure: The pressure at the outlet of a vacuum pump.
Expansion Joint: A flexible connector used to absorb thermal expansion and contraction in a piping system.
Explosion-Proof Pump: A pump designed to operate safely in hazardous environments where flammable gases or vapors are present.
F
Flange: A projecting rim or edge used to connect pipes, valves, or pumps to a piping system.
Flexible Coupling: A coupling accommodating slight misalignment between the pump and the motor.
Flooded Suction: A condition where the pump’s suction line is always filled with fluid, ensuring easy priming.
Flow Rate: The volume of fluid that a pump can move in a given amount of time, typically measured in gallons per minute (GPM) or liters per second (L/s).
Flushing: The process of cleaning a pump or piping system by circulating a cleaning fluid through it.
Foreline: The vacuum line connecting the vacuum system to the inlet of a vacuum pump.
Free Air Displacement: The theoretical volume of air a pump can move per unit time, measured at standard conditions.
G
Gas Ballast: A feature in some vacuum pumps that allows the introduction of a controlled amount of air to prevent condensation of vapors.
Gate Valve: A valve that uses a flat gate to control flow, providing a straight-through passage when fully open.
Gear Pump: A type of positive displacement pump that uses gears to move fluid.
Getter: A material used to absorb gas molecules in a vacuum system.
Gland Follower: A component that compresses the packing material in a stuffing box to create a seal.
Gland Packing: Material used to seal the space between the pump shaft and the casing, often made of graphite or PTFE.
Gland: A component that compresses packing material to create a seal around the pump shaft.
Globe Valve: A valve with a movable disk and stationary ring seat, used for regulating flow.
H
Head: The height at which a pump can raise fluid, often measured in meters or feet.
Helium Leak Detector: An instrument used to detect and measure leaks in a vacuum system using helium as a tracer gas.
Hydraulic Balance: The design feature balances hydraulic forces within a pump to reduce axial thrust.
Hydraulic Efficiency: The ratio of the pump’s hydraulic power output to the power input, excluding mechanical losses.
Hydraulic Gradient: The slope of the hydraulic grade line, representing the energy loss due to friction in a piping system.
Hydraulic Institute (HI): An organization that sets standards for pumps and pumping systems.
I
Impeller: A rotating component of a centrifugal pump that transfers energy from the motor to the fluid being pumped.
Inducer: A small impeller located at the pump’s suction inlet to reduce NPSH requirements and improve suction performance.
Inlet Pressure: The pressure of the fluid entering the pump.
Inlet Velocity: The speed at which fluid enters the pump, affecting NPSH and cavitation risk.
Ion Pump: A type of capture pump that uses an electric field to ionize and trap gas molecules.
J
Jet Pump: A pump that uses a jet of fluid to create a vacuum and move another fluid.
K
Knudsen Flow: A flow regime in which the mean free path of gas molecules is comparable to the dimensions of the vacuum system.
L
Labyrinth Ring: A ring with a series of grooves used to restrict fluid leakage in a pump.
Labyrinth Seal: A non-contacting seal that uses a series of grooves to restrict fluid leakage.
Lantern Ring: A ring placed in the stuffing box of a pump to distribute sealing fluid.
Leak Detector: An instrument used to identify and locate leaks in a vacuum system.
Leak Rate: The rate at which gas enters a vacuum system through leaks, typically measured in torr-liters per second.
Lobe Pump: A type of positive displacement pump that uses lobed rotors to move fluid.
M
Magnetic Drive Pump: A pump that uses a magnetic coupling to transfer power to the impeller without a direct mechanical connection.
Mass Spectrometer: An analytical instrument used to measure the mass-to-charge ratio of ions, often used in vacuum systems to analyze gas composition.
Mechanical Booster Pump: A pump used to increase the capacity and efficiency of a primary vacuum pump.
Mechanical Efficiency: The ratio of the pump’s mechanical power output to the power input, excluding hydraulic losses.
Mechanical Runout: The amount of deviation or wobble in a rotating pump shaft, which can affect seal performance.
Mechanical Seal: A device used to seal the rotating shaft of a pump to prevent leakage.
Micron: A unit of length equal to one-millionth of a meter, often used to measure vacuum levels.
Molecular Flow: A flow regime in which gas molecules move independently of each other, typically occurring at very low pressures.
Multistage Pump: A pump with multiple impellers to increase pressure in stages.
N
Needle Valve: A valve with a small, tapered point to precisely control flow, often used in instrumentation.
Non-Clog Pump: A pump designed to handle solids without clogging, often used in wastewater applications.
Non-Return Valve: Another term for a check valve, which prevents backflow.
NPSH (Net Positive Suction Head): The absolute pressure at the suction port of the pump, critical for avoiding cavitation.
O
Open Impeller: An impeller with vanes exposed on one or both sides, allowing solids to pass through more easily.
Open-Coupled Pump: A pump with a separate coupling between the motor and the pump, allowing for easier maintenance.
Orifice Plate: A plate with a hole used to control fluid flow in a piping system.
Outgassing Rate: The rate at which gas is released from materials within a vacuum system.
Outgassing: The release of gas from materials within a vacuum system.
P
Packing Gland: A component that holds the packing material in place and compresses it to create a seal.
Packing: Material used to seal the space between the pump shaft and the casing.
Partial Pressure: The pressure exerted by a single component of a gas mixture.
Peristaltic Pump: A type of positive displacement pump that moves fluid through a flexible tube by compressing it.
Pirani Gauge: A type of thermal conductivity gauge used to measure low vacuum pressures.
Piston Pump: A type of positive displacement pump that uses a piston to move fluid.
Plug Valve: A valve with a cylindrical or conical plug to control flow, offering quick operation.
Positive Displacement Pump: A pump that moves fluid by trapping a fixed amount and forcing (displacing) that trapped volume into the discharge pipe.
Pressure Gauge: An instrument used to measure the pressure of fluid in a pump or piping system.
Pressure Relief Valve: A valve that opens to release excess pressure in a pump or piping system to prevent damage.
Priming Chamber: A chamber in a self-priming pump that holds fluid to assist in priming.
Priming: The process of removing air from the pump and suction line to allow the pump to function properly.
Pump Curve: A graph showing the relationship between a pump’s flow rate and head, used to determine its performance.
Pump Jack: A device used to lift and lower the pump for maintenance or inspection.
Pumping Speed: The volume of gas a vacuum pump can remove per unit time, typically measured in liters per second (L/s).
R
Radial Bearing: A bearing that supports the pump shaft and resists radial forces.
Radial Flow Pump: A type of centrifugal pump where the fluid flows perpendicular to the pump shaft.
Radial Thrust: The force exerted perpendicular to the axis of the pump shaft, affecting bearing life and pump performance.
Reciprocating Pump: A type of positive displacement pump that uses a back-and-forth motion to move fluid.
Regenerative Pump: A type of vacuum pump that uses a rotating impeller to create a vacuum.
Rotary Piston Pump: A type of positive displacement pump that uses a rotating piston to create a vacuum.
Rotary Vane Pump: A type of positive displacement pump that uses rotating vanes to create a vacuum.
S
Scroll Pump: A type of dry pump that uses two interleaved spiral scrolls to compress and move gas.
Seal Chamber: The area in a pump where the mechanical seal is located.
Seal Flush: A system that circulates clean fluid to the mechanical seal to prevent contamination and cooling.
Seal: A device used to prevent leakage of fluid from the pump.
Self-Priming Pump: A pump designed to remove air from the suction line and prime itself.
Shaft Alignment: The process of aligning the pump shaft with the motor shaft to ensure smooth operation.
Shaft Runout: The amount of deviation or wobble in a rotating pump shaft, which can affect seal performance.
Shaft Seal: A seal that prevents fluid from leaking along the pump shaft.
Shaft Sleeve: A protective sleeve that fits over the pump shaft to prevent wear and corrosion.
Slurry Pump: A pump designed to handle abrasive or viscous fluids containing solid particles.
Solenoid Valve: An electrically operated valve that uses a solenoid to control flow, commonly used in automation.
Sorption Pump: A vacuum pump that removes gas by adsorption or absorption.
Sorption: The process of gas molecules being absorbed or adsorbed by a material.
Sputter Ion Pump: A type of ion pump that uses sputtering to remove gas molecules from a vacuum system.
Stuffing Box: A chamber in a pump where packing material is placed to create a seal around the shaft.
Submersible Pump: A pump designed to operate while fully submerged in the fluid it is pumping.
Suction Bell: A bell-shaped component at the pump’s suction inlet that helps direct fluid into the impeller.
Suction Lift: The vertical distance between the fluid source and the pump’s centerline.
Suction Strainer: A filter placed at the pump’s suction inlet to remove debris and prevent clogging.
T
Thermal Desorption: The release of adsorbed gas molecules from a surface by heating.
Thermal Relief Valve: A valve that opens to release excess pressure caused by thermal expansion in a pump or piping system.
Thermocouple Gauge: A gauge that measures vacuum pressure based on the thermal conductivity of gases.
Three-Way Valve: A valve with three ports, used to divert flow between two different paths.
Throttle Valve: A valve used to control the flow rate by varying the size of the flow passage.
Throughput: The amount of gas a vacuum system can process per unit time.
Thrust Bearing: A bearing that supports the pump shaft and resists axial forces.
Thrust Collar: A component that supports the pump shaft and resists axial forces.
Torr: A unit of pressure equal to 1/760th of an atmosphere, commonly used in vacuum measurements.
Trap: A device used to capture contaminants or vapors before they reach the vacuum pump.
Turbine Pump: A type of centrifugal pump with multiple stages and a high head.
Turbomolecular Pump: A high-vacuum pump that uses rapidly rotating blades to direct gas molecules towards the pump outlet.
U
Ultimate Pressure: The lowest pressure that a vacuum pump can achieve.
Ultimate Vacuum: The lowest pressure that a vacuum pump or system can achieve under ideal conditions.
V
Vacuum Chamber: A sealed enclosure from which air and other gases are removed to create a vacuum.
Vacuum Gauge: An instrument used to measure the pressure within a vacuum system.
Vacuum Valve: A valve designed to control the flow of gases in a vacuum system.
Valve Seat: The surface against which the valve disk or plug seals to stop flow.
Valve Stem: The rod that connects the actuator or handle to the valve disk or plug, transmitting motion.
Vane Pump: A type of positive displacement pump that uses vanes mounted on a rotor to move fluid.
Vapor Diffusion Pump: A type of diffusion pump that uses a vapor jet to create a vacuum.
Vapor Lock: A condition where vapor bubbles form in the pump or piping system, preventing normal fluid flow.
Vapor Pressure: The pressure at which a fluid will vaporize at a given temperature, important for avoiding cavitation.
Vapor Pressure: The pressure exerted by a vapor in equilibrium with its liquid or solid phase.
Viscosity: A measure of a fluid’s resistance to flow, affecting pump performance and efficiency.
Viscous Flow: A flow regime in which gas molecules interact frequently, typically occurring at higher pressures.
Viscous Fluid: A fluid with high resistance to flow, affecting pump performance and efficiency.
Volumetric Efficiency: The ratio of the actual volume of fluid pumped to the theoretical volume the pump should move.
Volute: A spiral-shaped casing of a centrifugal pump that converts kinetic energy into pressure energy.
Vortex Pump: A pump that uses a vortex created by an impeller to move fluid.
W
Wafer Valve: A type of butterfly valve that fits between two flanges, held in place by bolts.
Water Ring Pump: A type of vacuum pump that uses water as the working fluid to create a vacuum.
Wear Plate: A replaceable plate that protects the pump casing from wear caused by abrasive fluids.
Wear Ring: A replaceable ring that reduces leakage between the impeller and the pump casing.
Y
Y-Strainer: A device used to remove debris from the flow, protecting valves and other equipment.
Z
Zero Leakage Pump: A pump designed to operate without any fluid leakage, often used in hazardous or toxic applications.