You are looking to purchase the DeWalt air compressor. Assuming the compressor operates (outputs) air at...

You are looking to purchase the DeWalt air compressor. Assuming the compressor operates (outputs) air at 90psi and at 110F. If the atmospheric pressure is 0 psig and the atmospheric temperature is 65F, how much free air will the compressor consume in cubic feet (ft3 )/Minute to handle the 5 standard cubic feet per minute (SCFM)? • DeWalt Specifications -- 1.6 HP electric engine gets the job done. High-pressure motor with consistent draw requirements can be run with a 12-Gauge or higher extension cord that is under 50 ft. 200 psi maximum pressure enables long air-tool run time Delivers 5 SCFM at 90 psi for quick recovery time

Solutions

Expert Solution

When you speak of PD devices, either mass flowrate or volume flowrate at standard conditions (i.e scfm) remains constant irrespective of discharge pressure, keeping suction pressure constant, but actual volumetric flowrate (i.e acfm) changes. The calculation from scfm to acfm and vice-a-versa is ACFM = SCFM*[(Pstd - (Pvpstd*RHstd))/(P1-(P1*RH1))]*(T1/Tstd) Standard conditions are Pstd = 14.696 psia, Tstd = 60deg.F and RHstd = 0% P1, T1 and RH1 are pressurised air parameters. Generally, for small flowrates, the term P*RH can be neglected and the simplified formula will be ACFM = SCFM*(Pstd/P1)*(T1/Tstd) If the air temperature is same before and after compression (you can consider the temperature after aftercooler) then the equation is much simplified to ACFM = SCFM*(Pstd/P1) Likewise, CFM1/CFM2 = (P2/P1)*(T1/T2) All these terms are in absolute units. If your examples says the flowrate at 175psig is 25 acfm then at 90psig, it is 25*(175+14.696/90+14.696) = 45.3 cfm (at actual conditions) This method can be applied where you are reducing pressure by a pressure reducing valve after the air is compressed to 175psig at the compressor. If the compressor setting is changed to 90psig, rather, then adiabatic conditions are to be used for volumetric calculations.

Reference https://www.physicsforums.com/threads/calculating-cubic-ft-min-and-psi.155966/

samet mamat answered 1 year ago

Next > < Previous

Related Solutions

A gas turbine operates as a cold-air standard Brayton cycle. Air enetrs the compressor at 300K...

A gas turbine operates as a cold-air standard Brayton cycle. Air enetrs the compressor at 300K and 100kPa and is compressed to 700kPa. During the heat addition process in the combustor, the temperature of the air increases to 1000K. The turbine and compressor can be assumed to be operating isentropically. Evaluate specific heat at 300K. a. thermal efficiency of the cycle? b. net work of the cycle (kj/kg)? c. Back work ratio?

For these problems, assume air behaves as an ideal gas with R=0.287kJkgK. A compressor operates at...

For these problems, assume air behaves as an ideal gas with R=0.287kJkgK. A compressor operates at steady state and takes in air from ambient 0 kPa, gage and 200 K. The outlet pressure is 60 kPa, gage and 400 K. Determine: the mass flow rate if the inlet area is 20 cm2 and the inlet pressure is -5 kPa, gage. the minimum outlet temperature that is possible for this compressor. the isentropic efficiency of the compressor, assuming no heat loss....

A university student painter is considering the purchase of a new air compressor and paints a...

A university student painter is considering the purchase of a new air compressor and paints a gun to replace an old paint sprayer. (Both items belong to Class 9 and have a 25% CCA rate.) These two new items cost $12,000 and have a useful life of four years, at which time they can be sold for $1,600. The old paint sprayer can be sold now for $500 and could be scrapped for $250 in four years. The entrepreneurial student...

A university student painter is considering the purchase of a new air compressor and paint gun...

A university student painter is considering the purchase of a new air compressor and paint gun to replace an old paint sprayer. (Both items belong to Class 9 and have a 25% CCA rate.) These two new items cost $13,900 and have a useful life of four years, at which time they can be sold for $3,500. The old paint sprayer can be sold now for $690 and could be scrapped for $440 in four years. The entrepreneurial student believes...

A university student painter is considering the purchase of a new air compressor and paint gun...

A university student painter is considering the purchase of a new air compressor and paint gun to replace an old paint sprayer. (Both items belong to Class 9 and have a 25% CCA rate.) These two new items cost $13,700 and have a useful life of four years, at which time they can be sold for $3,300. The old paint sprayer can be sold now for $670 and could be scrapped for $420 in four years. The entrepreneurial student believes...

a university student painter is considering the purchase of a new air compressor and paint gun...

a university student painter is considering the purchase of a new air compressor and paint gun to replace an old paint sprayer. (Both items belong to Class 9 and have a 25% CCA rate.) These two new items cost $13,100 and have a useful life of four years, at which time they can be sold for $2,700. The old paint sprayer can be sold now for $610 and could be scrapped for $360 in four years. The entrepreneurial student believes...

An air compressor is operating at a steady state. The air enters at with a volumetric...

An air compressor is operating at a steady state. The air enters at with a volumetric flow rate 1.2 m^3/s at 170 kPa and 22 degrees celsius with negligible velocity and leaves at 1500 kPa with velocity of 200 m/s. The power to the compressor is 60 kW and the compressor is cooled at a rate of 15 kJ/kg. Determine the exit area.

You are a negotiator for a corporation that operates 12 hotels. You are looking for a...

You are a negotiator for a corporation that operates 12 hotels. You are looking for a chocolate maker to make gifts for your customers. Expect to offer 4000 boxes (4 small chocolates in a gift box) for $ 8.5 per box. However, the chocolate maker makes an initial counter offer of 2,500 boxes for $ 10 a box. As a negotiator, what should you do and what are your arguments and benefits for the chocolate maker to be able to...

Air enters the compressor of an ideal air standard Brayton cycle at 100 kPa and 290...

Air enters the compressor of an ideal air standard Brayton cycle at 100 kPa and 290 K with a mass flow rate (m⋅) of 6 kg/s. The compressor pressure ratio is 10. The turbine inlet temperature is 1500 K. If a regenerator with an effectiveness of 70% is incorporated in the cycle, determine (a) the thermal efficiency (ηth,Brayton) of the cycle. Use the PG model for air. (b) What-if Scenario: What would the thermal efficiency be if the regenerator effectiveness...

Air enters the compressor of a regenerative air-standard Brayton cycle with a volumetric flow rate of...

Air enters the compressor of a regenerative air-standard Brayton cycle with a volumetric flow rate of 100 m3/s at 0.8 bar, 280 K. The compressor pressure ratio is 20, and the maximum cycle temperature is 1800 K. For the compressor, the isentropic efficiency is 92% and for the turbine the isentropic efficiency is 95%. For a regenerator effectiveness of 86%, determine: (a) the net power developed, in MW. (b) the rate of heat addition in the combustor, in MW. (c)...

Subjects