pneumatics from greek: πνεύμα pneuma, meaning breath of life is a branch of engineering that makes use of gas or pressurized air.. pneumatic systems used in industry are commonly powered by compressed air or compressed inert gases.a centrally located and electrically powered compressor powers cylinders, air motors, and other pneumatic devices.a pneumatic system controlled through .
a typical, subsonic diffuser is a duct that increases in size in the direction of flow. as the duct increases in size, fluid velocity decreases, and static pressure rises. both mass flow rate and bernoulli's principle are responsible for these changes in pressure, and velocity. 1 supersonic diffusers. supersonic diffusers.
nominal pipe size nps is a north american set of standard sizes for pipes used for high or low pressures and temperatures. ' nominal' refers to pipe in non-specific terms and identifies the diameter of the hole with a non-dimensional number for example – 2-inch nominal steel pipe' consists of many varieties of steel pipe with the only criterion being a 2.375-inch 60.3 mm outside diameter .
heating, ventilation, and air conditioning hvac is the technology of indoor and vehicular environmental comfort. its goal is to provide thermal comfort and acceptable indoor air quality. hvac system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics and heat transfer.
process duct work conveys large volumes of hot, dusty air from processing equipment to mills, baghouses to other process equipment. process duct work may be round or rectangular. although round duct work costs more to fabricate than rectangular duct work, it requires fewer stiffeners and is favored in many applications over rectangular ductwork.
duct leakage testers are used in residential single family, residential multi-family, and commercial buildings that have a forced air delivery systems for heating and cooling. operation edit a basic duct leakage testing system includes three components: a calibrated fan, a register sealing system, and a device to measure fan flow and building pressure.
a duct with less than 0.75 mg/100m 2 is considered to be clean, per the nadca standard. a hong kong standard lists surface deposit limits of 1g/m 2 for supply and return ducts and 6g/m 2 for exhaust ducts, or a maximum deposit thickness of 60 µm in supply and return ducts, and 180 µm for exhaust ducts.
compressible duct flow with friction. this article concerns a gas flow with friction due to the boundary walls under consideration. this problem is same as the moody type pipe-friction problem but with considerably larger changes in friction, kinetic energy and enthalpy of the flow.
isolated-phase bus is made in ratings from 3000 amperes to 45,000 amperes, and rated for voltages from 5000 volts up to about 35,000 volts. in the larger current ratings, dry air is forced through the enclosures and within the tubular conductors for forced-air cooling of the conductors. the cooling air is recirculated through a heat exchanger.
air changes per hour, abbreviated acph or ach, or air change rate is a measure of the air volume added to or removed from a space normally a room or house divided by the volume of the space. if the air in the space is either uniform or perfectly mixed, air changes per hour is a measure of how many times the air within a defined space is replaced.
hvac heating, ventilation, and air conditioning is a major subdiscipline of mechanical engineering. the goal of hvac design is to balance indoor environmental comfort with other factors such as installation cost, ease of maintenance, and energy efficiency. the discipline of hvac includes a large number of specialized terms and acronyms, many .
a pneumatic actuator mainly consists of a piston or a diaphragm which develops the motive power. it keeps the air in the upper portion of the cylinder, allowing air pressure to force the diaphragm or piston to move the valve stem or rotate the valve control element. valves require little pressure to operate and usually double or triple the .
the most common application for an air-mixing plenum is the mixing of return air or extract air with fresh air to provide a supply air mixture for onward distribution to the building or area which the ventilation system is serving. the air transferred from the return air stream to the supply air stream is termed recirculated air.
underfloor air distribution ufad is an air distribution strategy for providing ventilation and space conditioning in buildings as part of the design of a hvac system. ufad systems use an underfloor supply plenum located between the structural concrete slab and a raised floor system to supply conditioned air through floor diffusers directly into the occupied zone of the building.
they can be fabricated through rolling preferable for ducts of 12' or more in diameter or extruded for ducts up to 18' . hvac systems do not include this category of industrial application, namely exhaust systems. a distinction from hvac system ducts is that the fluid air conveyed through the duct system may not be homogeneous.
a diffuser is 'a device for reducing the velocity and increasing the static pressure of a fluid passing through a system”. the fluid's static pressure rise as it passes through a duct is commonly referred to as pressure recovery. in contrast, a nozzle is used to increase the discharge velocity and lower the pressure of a fluid passing through it. .
pneumatic logic is a reliable and functional control method for industrial processes. in recent years, these systems have largely been replaced by electronic control systems in new installations because of the smaller size, lower cost, greater precision, and more powerful features of digital controls. pneumatic devices are still used where .
a dedicated outdoor air system doas is a type of heating, ventilation and air-conditioning system that consists of two parallel systems: a dedicated system for delivering outdoor air ventilation that handles both the latent and sensible loads of conditioning the ventilation air, and a parallel system to handle the mostly sensible heat loads generated by indoor/process sources and those .
the limiting case of the venturi effect is when a fluid reaches the state of choked flow, where the fluid velocity approaches the local speed of sound. when a fluid system is in a state of choked flow, a further decrease in the downstream pressure environment will not lead to an increase in the mass flow rate. however, mass flow rate for a .