Glossary

API Standards for Blowers and Compressors
API Standards are a set of technical guidelines issued by the American Petroleum Institute to promote safe, reliable, and efficient operation of blowers and compressors. These standards are widely applied in demanding industrial environments, particularly within the oil, gas, petrochemical, and chemical industries.

Commonly Referenced API Standards

• API 617 – Defines requirements for the design, testing, and operation of centrifugal and axial compressors used in petroleum, chemical, and gas services.

• API 672 – Covers packaged centrifugal and integrally geared compressors, typically used in process gas applications.

• API 673 – Specifies design and performance requirements for centrifugal fans in petroleum, chemical, and gas industries.

• API 681 – Addresses liquid ring vacuum pumps and compressors.

Why API Standards Matter

• Promote uniform quality and dependable performance

• Enhance operational safety by addressing factors such as vibration limits, material selection, and sealing systems

• Support compatibility, easier maintenance, and long-term reliability through standardized design practices

An axial fan is a type of fan in which air or gas flows in the same direction as the rotating shaft. It is typically used where large volumes of airflow are needed at relatively low pressure. The fan operates using blades attached to a central hub that rotate to move the air forward.

A compressor in which gas flows parallel to the axis of the rotating shaft. Used in applications requiring high volumes of gas at medium to high pressures.

Fan or impeller blades designed to curve away from the direction of rotation, offering high efficiency at good pressure numbers and low noise.

The process of adjusting the distribution of mass in a rotor to minimize vibration during operation.

Static balancing ensures the mass distribution of a rotor is even so it remains stationary without tilting, correcting unbalance in one plane. Dynamic balancing, performed while the rotor is spinning, addresses unbalance in multiple planes to prevent vibrations during operation.

A mechanical component that supports the rotating shaft and reduces friction between moving parts.

A belt drive is a mechanical system that transmits power between rotating shafts using a flexible belt, typically made of rubber or synthetic materials. It is commonly used in industrial machinery to transfer motion efficiently, dampen vibrations, and accommodate misalignment between shafts.

A compressor that increases gas pressure by accelerating it through an impeller and then decelerating it in a diffuser.

A fan that moves air or gas perpendicular to the axis of rotation, typically used for medium-to-high-pressure applications.

A device used to connect two shafts e.g.(impeller shaft and motor shaft) together at their ends to transmit power.

The rotational speed at which resonance occurs in a rotating system, potentially causing vibrations or damage.

A stationary component in fans or compressors that slows down airflow and converts velocity into pressure.

The discharge side of a pump, blower, or compressor is the outlet where the fluid (liquid or gas) exits the machine after being pressurized or moved. This side typically operates at a higher pressure than the suction side and is connected to the system or process requiring the pressurized fluid.

The ratio of useful work output to total energy input in a system, typically expressed as a percentage.

HAZOP (Hazard and Operability Study) is a systematic and structured technique used to identify potential hazards and operability issues in a process, system, or operation. It is commonly applied in industries such as chemical, oil & gas, and manufacturing to ensure safety and efficiency.

The rotating component of a fan, pump, or compressor that imparts energy to the fluid.

Adjustable vanes located at the inlet of a fan or compressor to control the airflow and optimize performance.

A heat exchanger used to cool gas between compression stages in a multi-stage compressor.

A device used to prevent leakage of fluids from rotating machinery, commonly found in pumps and compressors.

A monoblock bearing is a single-piece bearing housing that integrates both the structural support and the bearing assembly into a unified unit. This design eliminates the need for separate components, improving rigidity, alignment, and reducing the potential for misalignment or assembly errors. SERAFIMA monoblock bearings are commonly used in high-performance or compact applications where durability and precision are critical.

A comprehensive inspection, cleaning, repair, and replacement of components to restore a machine to its original specifications.

A performance chart for a blower or compressor graphically represents the relationship between flow rate, pressure, efficiency, and power consumption across operating conditions. It helps determine the optimal operating range, avoid surge or choke conditions, and ensure efficient performance.

The ratio of the outlet pressure to the inlet pressure in a compressor.

The rotating part of a machine, including the shaft, blades, and impeller, which imparts energy to the fluid.

A spiral casing surrounding an impeller in pumps and fans to collect and direct fluid flow efficiently.

The central axis in a rotating machine that transmits mechanical power.

A shaft sleeve is a cylindrical protective cover fitted over a rotating shaft, typically in pumps, blowers or compressors, to shield it from wear, corrosion, and erosion caused by mechanical seals, Turbolabyrinth seals, packing, or fluid contact. Shaft sleeves are replaceable components that extend the life of the shaft and are commonly made from durable materials like stainless steel, bronze, or other alloys.

SIL (Safety Integrity Level) is a measure of the reliability and effectiveness of a safety instrumented function (SIF) in reducing risk in industrial processes. Defined in the international standards IEC 61508 and IEC 61511, SIL levels range from 1 to 4, with higher levels indicating greater risk reduction and reliability.

The side of a pump, fan, blower or compressor where fluid enters the system.

Surge condition in compressors or blowers occurs when the flow rate through the machine drops below a critical level, causing unstable operation characterized by flow reversal, pressure fluctuations, and vibrations. It can damage equipment and reduce efficiency, making it essential to avoid by maintaining operation above the surge limit defined in the performance chart.

A bearing that absorbs axial forces generated in a rotating machine.

Tip speed refers to the linear velocity of the outermost edge of a rotating component, such as a fan blade, impeller, or turbine blade.

It is calculated as: Tip Speed=ω⋅r

where:

• ω\ is the angular velocity (in radians per second).
• r is the radius (distance from the center of rotation to the blade tip).

A TURBLABYRINTH SEAL is a type of restrictive ring seal commonly used in rotating equipment, where a carbon ring or several carbon rings (alternatively PTFE rings), often split for easier installation, is pressed against the rotating shaft or a mating surface. It provides a reliable seal by leveraging carbon's low friction and high-temperature resistance, making it ideal for applications like compressors, turbines, and pumps operating under extreme conditions.

The range of operating flow rates over which a machine can maintain efficient and stable performance.

A diagnostic technique used to monitor the condition of rotating equipment by analyzing its vibration patterns.

A spiral casing surrounding an impeller in pumps and fans to collect and direct fluid flow efficiently.

A replaceable ring fitted to reduce leakage between high-pressure and low-pressure zones in pumps and compressors.