From Mechanical Engineering License Review, Fifth Edition
With the exception of the fact that gases are compressible the theory of design for equipment to move gases and vapors is similar to that of pumps for liquids. Heads developed in terms of feet of fluid being pumped are almost identical for equivalent circumferential speeds as for centrifugal pump designs. Axial flow impellers impart similar heads to both liquids and gases and valve actions in positive displacement compressors are quite similar to those of piston water pumps.
When considering the compression of gases, the machines are usually referred to as fans (centrifugal and propeller), blowers (centrifugal and lobular), and compressors (multistage centrifugal, lobular, and piston).
FANS AND BLOWERS
Find the motor size needed to provide the forced-draft service to a boiler that burns coal at the rate of 10 tons per hr. The air requirements are 59,000 cfm, air is being provided under 6 in. water gauge (WG) by the fan which has a mechanical efficiency of 60 per cent. Assume fan to deliver at a total pressure of 6 in. WG.
A blower with the inlet open to the atmosphere delivers 3,000 cfm of air at a pressure of 2 in. WG through a duct 11 in. in diameter, the manometer being attached to the discharge duct at the blower. Air temperature is 70 F, and the barometer pressure is 30.2 in. Hg. Calculate the air horsepower.
The horsepower is determined by the basic formula given as
We must convert the 6 in.
Products & Services
Industrial fans and blowers are move air and ganular media in industrial and commercial settings. Typical applications include air circulation for personnel, exhaust, or material handling.
Topics of Interest
15-1 Basic Principles of Heat Transmission Problems of greatest importance and most frequently occurring in the entire field of engineering are unquestionably those that involve the strength of...
In general terms, a pressure blower provides relatively high pressure at low volume when compared to other types of centrifugal fans. For purposes of this letter, fans with volumes to 10,000 CFM with...
AIR HANDLING AND VENTILATION A fan is a gas flow producing machine which operates on the same basic principles as a centrifugal pump or compressor. Each of these devices, including fan, converts...
COMPRESSORS, FANS, BLOWERS AND VACUUM PUMPS Fans are used to raise the pressure by about 3% [12 in. (30 cm) water], blowers raise to less than 2.75 barg (40 psig), and compressors to higher pressures,...
5.1 Introduction In most HVAC systems, the final energy transport medium is moist air a mixture of dry air and water vapor. This is conveyed through filters, heat exchange equipment, ducts, and...