Steam Main Jargon Buster


A heat exchanger typically used in the brewing industry to evaporate liquor (water).


This is a scale forming element found in boiler feed water.


A type of laundry machine. It typically consists of large heated rollers over which wet fabric is passed to dry.


A type of heat exchanger. It uses a shell with tubes inside it. It works by heating the fluid circulated over the tubes/coils. It can be storage or non-storage. Some calorifiers may have two separate tube bundles (the second being the condensate cooler to help condense any flash steam and increase efficiency).

Capacitance probe

A type of probe used to measure the level of a liquid. A capacitance device consists of two conducting objects/plates with a dielectric material between them. Therefore a typical capacitance probe consists of a conducting cylindrical probe covered in a dielectric material (normally PTFE). As the level of the conductive liquid changes so does the capacitance reading from between the probe and the chamber/tank wall/boiler shell (which acts as the second conductive object). This reading can therefore be used to measure the level of the liquid.

Carbon steel

A material which consists of iron and smaller amounts of carbon to make an alloy called carbon steel. Carbon works as a strengthening instrument in steel. It does this by further solidifying the structures inherent in iron. By adjusting the amount of carbon present in the alloy the properties of the final material can be changed to suit the application.


On a steam boiler this is where there is foaming in the boiler which is fed into the steam system. This condition is caused by too high a TDS level in the boiler water and is aggravated when the boiler is operating under high demand.

Cascade control

Where a single process is controlled by using two independent variables. These two variables are controlled by using a slave and master controller. A real world example of this might be a single control valve which gets a signal from the master controller with its own sensor. This master controller also gets a signal from a slave controller with its own sensor. This way two variables can be used to control the single valve.

Cast iron

A widely used engineering material. It has a low melting point, good fluidity, is easily cast, has excellent machinability, good resistance to deformation and wear, as well as being resistant to oxidisation (rust).Cast iron (grey cast iron) is however brittle. To overcome this on steam systems a nodular cast iron (commonly known as SG iron) is normally used as it does not have the brittle fracture mode of normal cast iron.

Caustic soda

A common name for a water treatment chemical, sodium hydroxide. It is high in alkalinity, so is added to boiler water to reduce acidity in the boiler.


A term normally associated with the operation of a pump. Cavitation in a pump should be avoided. It is caused by the formation and collapse of vapour cavities in a flowing liquid. Such vapour cavities can form in a flowing liquid where the local pressure is reduced to that of the liquid vapour pressure at the temperature of the flowing liquid. Collapse of these bubbles will begin when they are moved into regions where the local pressure is higher than the vapour pressure. Collapse of these cavities may produce objectionable noise, vibration, and corrosion or pitting of the boundary materials in the region of the bubble collapse. An important effect of cavitation in liquid handling facilities is the decrease in the performance and efficiency of equipment.


Climate Change Agreement. This is an agreement between UK industry and DEFRA that has agreed targets for energy efficiency and carbon emission reductions.


Combined Cycle Gas Turbine. This is a gas fired turbine electricity generation plant, which uses waste heat to power a steam turbine.


Climate Change Levy. This is a UK tax on the use of energy delivered to non-domestic users.

Check valve

A valve which allows fluid to flow in only one direction through it. Commonly called a 'non-return valve'.

Chemical feed line

A pipeline which feeds the boiler treatment chemicals into the boiler feed line.


This is a process in which chlorine gas or a chlorine compound is added to water, normally for the purpose of disinfecting.


Combined heat and power. Where both electricity and heat energy is generated.


An acronym for the Chartered Institute of Building Services Engineers. It is a body which represents and provides services to the building services profession.


This means 'cleaning in place';. It is where plant is permanently piped up to enable a backwash cleaning operation with diluted acids and detergents. It is then rinsed to make clean.

Clean room

A room or part of a factory which is 'sealed' so the processes can be guaranteed to be free from bacterial contamination. Mechanical plant providing services to these rooms are of the highest standard. Human access and activity is strictly controlled. It is typically used in the pharmaceutical and semi-conductor industry.

Climate Change Levy (CCL)

A UK tax on energy delivered to non-domestic users. Tax is not charged on electricity generated from new renewables and approved cogeneration schemes however.

Closed loop control

This is a control algorithm or system in which the control output is calculated from measurements of the process output.


carbon dioxide. This it is produced by burning carbon, and absorbed by plants during photosynthesis. It is the best known greenhouse gas, and is therefore used as an international standard to measure and reduce climate change.

Combustion efficiency

This is the ratio of heat passed into the boiler water relative to the heat contained in the fuel burnt to provide it. The difference being; losses to atmosphere via the flue gases.


When steam has exchanged its heat it condenses into condensate (hot water).

Condensate recovery

The process of recovering condensate. Condensate is normally pumped back into the boiler feedwater tank. Retaining this in the system saves; water, chemicals and heat.


The process of changing from a gas to a liquid (steam changing into water).

Conductivity meter

A device that measures the conductivity of a liquid and thus enables the degree of purity to be established. Typical use would be to determine the amount of dissolved solids in boiler water, which can be directly related to its conductivity level.

Conductivity probe

A type of probe which is used either to control the TDS in a steam boiler or trigger an action (e.g. a valve, pump or relay). A voltage is supplied to two electrodes and the electrical resistance (and change of) from the solution between the electrodes can be measured and used as stated above.


Elements used to mechanically make or break an electrical circuit.

Control panel

A box housing control equipment.

Control valve

A type of valve used to control; flow, pressure, temperature, and liquid level. Typically it consists of a valve body with a plug which moves up and down. This plug fully or partially opens or closes in response to signals sent from a controller. This opening or closing is done by use of electrical, hydraulic or pneumatic actuators.

Coppus steam turbine

A type of steam turbine made by the Coppus company in Massachusetts USA. Its turbines were very popular in the Oil and Petrochemical industry sector. Coppus steam turbines are now part of the Dresser Rand company range.


A type of pressure reducing valve manufactured by TLV for use on steam. The valve incorporates a strainer, separator, and steam trap in-built into the lower part of the pressure reducing valve. Generally the strainer is a two layer screen, the separator is a cyclonical type, and the steam trap is a free float type.

Critical pressure drop (CPD)

On a valve steam flows through due to a pressure difference (inlet pressure is higher than the pressure downstream of the valve). The flow rate of steam passing through the valve will increase in line with this differential pressure. However a point is reached when further lowering of the downstream pressure cannot increase the flow rate through the valve. This condition is known as 'critical pressure drop'.


Condensate recovery unit. A system normally consisting of; a reservoir/tank, controller, and a pump. The unit will normally pump condensate back into the boiler feedwater tank.


An acronym used in the hospital sector for Central Sterilising Services Department.

Culinary steam

This is steam of the quality acceptable for use within the food industry.

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