This glossary serves to introduce the user to some of the terminology used throughout
this website. These descriptions are proposed to serve as a reference point in product
discussions to eliminate problems with definition. While these terms are subject to different
interpretation throughout various technologies, it is proposed that these definitions
be adhered to throughout industry, to unify their usage.
Accuracy: The degree of closeness of a measured value to the intended, specified, or actual value. Compare to PRECISION.
Ambient Temperature: Temperature of the media surrounding external surfaces of a part.
Burst Pressure: The maximum pressure a part can endure before it will break.
Coefficient of Variation (CV): This value, expressed in terms of percentage, reflects the dispersion of data used to help define consistency of performance. It is calculated by taking the standard deviation of a distribution and dividing it by the mean value.
Coil Voltage: Voltage at which the coil must energize if the solenoid valve is to perform as stated in the specifications.
Continuous Duty: Coils rated for continuous duty are designed to be energized continuously without overheating to failure.
Cross-Over Volume (Carry-over Volume): Any internal geometry dependent volumetric error introduced by the internal volume of a solenoid valve between the valve point and the common flow point. This is most commonly used in discussions of 3-way valve models as it refers to the unwashed slug of material between the flowing passage and the closed port seal.
Crosstalk (Intra-port Flow): Any response time dependent flow or pressure variation between any two valves or two ports of a 3-way valve. For example, this term refers to the flow that takes place between the normally closed and normally open ports of the 3-way valve in the time between the beginning of actuation and the end of actuation, when both ports are partially open.
Dead-Volume: The actual non-flushable volumes of any component or system flow passages, where a dead-end passageway or cavity could retain materials to contaminate subsequent sample or flow media. This value is highly subjective, as many factors come into play to determine the actual dead volume such as miscibility, viscosity, binding energy, etc. The quantity of the former sample still retained inside the component after flushing with some specified volume is defined as dead volume.
De-energized: No power applied to the coil. A normally closed solenoid valve is closed when the coil is de-energized.
Duty Cycle: The ratio, expressed in terms of percentage, of the energized period to the total period. Example, if a solenoid valve is on for 8 seconds and off for 12 seconds, the total cycle time is 20 seconds and therefore the duty cycle is 40%.
Energized: Power applied to the coil causing the solenoid valve to change state. A normally closed valve will open when energized.
Filter: A device used to remove contaminants from the fluid media.
Normally Closed: A normally closed solenoid valve is closed when de-energized, preventing flow. When energized, the valve opens, allowing flow.
Normally Open: A normally open solenoid valve is open when de-energized, allowing flow. When energized, the valve closes, preventing flow.
Operating Pressure: The pressure specified for normal operation.
Precision: The degree of closeness of two or more measurements to each other. Compare to ACCURACY.
Pressure Differential: The pressure difference between the inlet and outlet pressure.
Proof Pressure: The level of pressure that may be applied to the part without causing permanent damage.
Response Time: This term defines the lag time between the input of a control signal, and the resulting response of the system or component being monitored. Typical use of the response time with a passive component could define the time lag between a pressure pulse input to a check valve, and the time to close or open the valve seat in response to that pulse. The more common usage is in reference to active components, such as solenoid valves. This term then typically defines the time from beginning of a normal voltage step-input drive signal, and the pneumatic output from the valve port that is opening or closing as a result of that signal.