** So the high-speed effective compression ratio may be approximated by multiplying the base 9**.0:1 mechanical ratio by 0.95 to get 8.55:1 Step 2 Calculate basic compression pressure from the two low- and high-speed effective compression ratios of 7.32:1 and 8.55:1, respectively, assuming standard sea-level atmospheric pressure of 14.7 pounds per. The pressure ratio equals the value RP =1 for V J =2·C F. The corresponding operation pressure would be p≅4·10 3 MPa. This high value can not be realised by commercial plunger pumps or pressure intensifiers. For a rather low pressure, say 30 MPa, the pressure ratio is about R P =11 Compression Ratio The compression ratio is the ratio of the absolute discharge pressure (psia) to absolute suction pressure (psia), found using the formula Discharge Pressure Absolute ÷ Suction Pressure Absolute. In that chart that accompanies part one of this series, the left side (Y-axis) represents compression ratios Compression ratio is a ratio of volumes. In the case of the Otto cycle reciprocating engine, the maximum expansion of the charge is limited by the mechanical movement of the pistons (or rotor), and so the compression can be measured by simply comparing the volume of the cylinder with the piston at the top and bottom of its motion Compression Ratio is based on the Ideal Gas Law and is the ratio between Discharge Pressure Absolute and Suction Pressure Absolute. CR = pd / ps (1

For example, at Denver's 5000 feet elevation, the atmospheric pressure is typically around 12.4 psia. The high-speed value This is important when determining P2c. Compression ratio (R) is the ratio of discharge pressure (Р 2) to suction pressure (Р 1) in compressor, Р2/Р1. Calculating (actual) compression pressure in automotive engines is not a straightforward process of comparing. With regard to turbine engines, the **compressor** and the turbine both have a property called the **PRESSURE** **RATIO**. For the **compressor**, pitot tubes are placed upstream and downstream to measure dynamic **pressure**. A single-stage centrifugal **compressor** will typical offer a **pressure** **ratio** of 4:1 Compression ratio (R) - is the pressure ratio at discharge to suction pressure: R = Pd/Ps (where Pd and Ps are absolute). One stage compressor has only one R value. Two stage compressors have 3 R values The EPR is simply the product of the pressure ratio across all of the engine components. EPR = pt8 / pt2 = (pt3 / pt2) * (pt4 / pt3) * (pt5 / pt4) * (pt8 / pt5) EPR = compressor pressure ratio * burner pressure ratio * turbine pressure ratio * nozzle pressure ratio Let subscripts 1 and 2 stand for inlet and outlet process conditions of the compressor. Then the pressure ratio of the compressor is P 2 /P 1. P 2 /P 1 = (V 1 /V 2) n..

- If you divide the amount of power that goes into building pressure by the total power put into the compressor, you get the efficiency of the compressor. For example, if the compressor is 70% efficient, this means that 70% of the power put into the compressor is used in building air pressure. The other 30% of the power is used heating up the air
- Step 1 : calculate the mass flow rate The compressor is to deliver 2000 Nm3/h of air. Normal conditions are here defined as 101325 Pa and 0°c, at this pressure gas ideality is mostly verified thus the specific gravity is PM/RT/1000 = 1.294 kg/m3. This gives a mass flowrate of 2000*1.294 = 2587 kg/h
- Ps SUCTION PRESSURE The pressure at the compressor inlet expressed as psia (or Bar-a). Pd DISCHARGE PRESSURE The pressure at the compressor discharge expressed as PSIA (or Bar-a). In the example, the suction and discharge pressures are given as 5 and 65 psi respectively. As mentioned above, we have to know whether he means 'psia' or 'psig'
- ◊ Pressure Ratio • Pressure Ratio () is defined as the Absolute outlet pressure divided by the Absolute inlet pressure. Where: o = Pressure Ratio o P2c = Compressor o Discharge Pressure o P1c = Compressor Inlet Pressure • It is important to use units of Absolute Pressure for both P1c and P2c
- One of the critical parameters in compressor design and selection is the compression ratio, often denoted as r. The compression ratio is simply the ratio of the absolute stage discharge pressure to the absolute stage suction pressure.. Because most gases increase in temperature when they are compressed, the final compressor outlet temperature is always a concern
- The total temperature ratio Tt3 / Tt2 across the compressor is related to the pressure ratio by the isentropic flow equations. Tt3 / Tt2 = (pt3 / pt2) ^ ((gam -1) / gam) where gam is the ratio of specific heats. Work must be done to turn the shaft on which the compressor is mounted

Thus the compressor pressure ratio is equal to PR = 2.41. Moreover we know, that the compressor receives gas (point 1) at the figure: p 1 = 2.78 MPa; T 1 = 299 K (26°C) the isentropic compressor efficiency η K = 0.87 (87%). The heat capacity ratio, , for helium is equal to =c p /c v =1.66. Calculate: the heat added by the heat exchanger. The pressure ratio is not affected by the change in inlet pressure to the compressor. The outlet temperature will remain constant at T 2 = T 2e = 632.18 K or 359.18 C. Step 11. The outlet pressure of the compressor will be, P 2 +P 2 = r p(P 1 +P 1) = 11.0×(1.0−0.01226) = 10.8651 bar The inlet pressure to the turbine will be, P 3 = When considering a film thickness tolerance, the minimum value of pressure ratio is set to β = 0.4 at the upper clearance ho (U) and lower power ratio K = 3. Maximum pressure ratio β = 0.7 then corresponds to the lower clearance ho (L) and upper power ratio K = 9. This is further described below. View chapter Purchase boo

To calculate centrifugal compressor power, we need these gas properties: compressibility factor (Z), molecular weight (MW), inlet gas temperature, inlet gas pressure, outlet gas pressure, adiabatic component (Cp/Cv), and mass flow rate. Let's start with an example while I show you step-by-step of the calculation method This video derives the formula for the maximum permissible compressor ratio for a Gas Turbine Engine given a maximum turbine entry temperature Then, divide the result by the cylinder volume to find the compression ratio. For instance, if the swept volume is 458.38 and the clearance volume is 53.7, start by adding 458.38 and 53.7, which is 512.08. Divide 512.08 by 53.7, which is 9.5359. So, the compression ratio is 9.54:1

As you increase operating pressure, the temperature rises into the pump and volumetric efficiency decreases, leading to a little decrease in capacity. This is why some manufacturers will post for example a capacity of 20 cfm at 90 psi and 18 cfm at 125 psi for the same compressor. You cannot calculate it, you must measure it In general, increasing the pressure ratio is the most direct way to increase the overall thermal efficiency of a Brayton cycle, because the cycle approaches the Carnot cycle. According to Carnot's principle higher efficiencies can be attained by increasing the temperature of the gas.. But there are also limits on the pressure ratios that can be used in the cycle

Pressure Ratio = Pressure Ratio ≈ 1.41 Here's the rest of the information in a table: We see three sets of runs at around 100 °F ambient using engine speeds of 4,000 and 6,000 RPMs at 6 psi of boost * Pressure Ratio - Brayton Cycle - Gas Turbine*. The thermal efficiency in terms of the compressor pressure ratio (PR = p 2 /p 1), which is the parameter commonly used:. In general, increasing the pressure ratio is the most direct way to increase the overall thermal efficiency of a Brayton cycle, because the cycle approaches the Carnot cycle. According to Carnot's principle higher.

- The vertical axis represents the pressure ratio of the compressor. It is calculated by taking the absolute outlet pressure and dividing by the absolute inlet pressure. (Note, most gauges read in gauge pressure i.e. zero psi at atmospheric when it is actually around 14.7 or so psi.
- Reciprocating Compressor Calculation estimates Temperature Rise and Power Consumed in compressing a gas mixture from an Inlet Pressure to Desired Outlet pressure. CheCalc Chemical engineering calculations to assist process, plant operation and maintenance engineers
- Calculating Pressure Ratio (PR= P2c / P1c) Pressure ratio is a variable equation that combines ambient pressure with gauge pressure divided by ambient pressure. This identifies where the compressor will perform its max duty cycle. Knowing pressure ratio is a key component to selecting the correct turbo for your application
- Free Shipping Available. Buy Compressor pressure on eBay. Money Back Guarantee

* How to convert compression ratio to psi? First, determine the compression ratio*. Calculate or measure the compression ratio. Next, determine the pressure. Calculate or measure the atmospheric pressure. This is 14.696 PSI at sea level. Finally, calculate the PSI. Calculate the PSI using the equation above An easy formula to work with is to subtract the reading in inches from 30 inches and divide the answer by two. We can now solve the formula for finding the compression ratio The proper equation would be the Bernoulli equation: P₁ + ¹/₂ρv₁² + ρgh₁ = P₂ + ¹/₂ρv₂² + ρgh₂, where P is pressure for instances 1 and 2, v is their respective velocities, rho (ρ) is a constant that you must find, and for the purposes of air compressors, g and h are not needed as we are assuming that gravity (g) is a constant and the heights (h) at which all the measurements are taken do not change

Thus the compressor pressure ratio is equal to PR = 2.41. Moreover we know, that the compressor receives gas (point 1) at the figure: p 1 = 2.78 MPa; T 1 = 299 K (26°C In A/C and refrigeration the compression ratio is simply the absolute discharge pressure leaving the compressor divided by the absolute suction pressure entering the compressor. Absolute pressure is just gauge pressure + atmospheric pressure ** Vertical Axis The vertical axis represents the pressure ratio of the compressor**. It is calculated by taking the absolute outlet pressure and dividing by the absolute inlet pressure. (Note, most gauges read in gauge pressure i.e. zero psi at atmospheric when it is actually around 14.7 or so psi. Note it is more typical to work with the compressor pressure ratio rather than the temperature ratio so we will substitute the isentropic relationship: into the equations before plotting the results in Figures 11.16 , 11.17 , and 11.18

Many times we have noticed users ask us how to determine the revolutions per minute (rpm) of the air compressor without using an rpm checking device. Or they would ask that after changing the electric motor from a 50Hz to a 60Hz frequency the rpm of the motor is higher so what size should the motor pulley be to ensure the same effective rpm on the compressor flywheel Calculate the power required to overcome the internal losses in an electrically driven turbo compressor operating under the following conditions: Suction volume : 1140 m^2/min Temperature : 27 ˚C Pressure : 0.85bar (abs) Deliver temperature : 104 ˚C Pressure : 6.5bar (abs) Motor load : 5850

- The temperature ratio across the compressor, . In terms of compressor temperature ratio, and using the relation for an adiabatic reversible process we can write the efficiency in terms of the compressor (and cycle) pressure ratio, which is the parameter commonly used
- Note : in case of multi staged compressor, if the compression ratio of each stage is unknown, it can be assumed at 1st approximation that τ one stage =τ1/n T 1 =Temperature entry compressor (K) p 1 =Initial pressure (bar abs) T 2 =Temperature outlet compressor (K) - isentropic discharge temperatur
- (Motor full-load bhp) x (.746 kW/hp) x (1/0.9 motor efficiency) x (Annual hours of operation) x (Electricity cost in $/kWh) This equation assumes the compressor is 90 percent efficient, which you can adjust at the.9 input
- Compressor characteristic is a mathematical curve that shows the behaviour of a fluid going through a dynamic compressor.It shows changes in fluid pressure, temperature, entropy, flow rate etc.) with the compressor operating at different speeds.. A compressor increases the pressure of a fluid passing through it, so that the exit pressure is higher than the inlet pressure
- g. A high-CR engine will lose some of that compression pressure if the intake valve remains open t after the piston starts the compression stroke
- compressor kicks in and once at the moment the compressor kicks out. 5. Take the psig indicated on the compressor's tank gauge when the compressor kicked in and subtract it from the psig indicated when the compressor kicked out. For example, if the compressor kicks in at 75 psig and kicks out at 100 psig then the difference would be 25 psig. 6
- Page 1 of 2 - Calculate Inter Stage Pressure In Multistage Reciprocating Compressor - posted in Student: Hi I have one problem regarding inter stage pressure in multi stage reciprocating compressor. I have four stage reciprocating compressor with inter cooler. I also have inlet and discharge pressure. here volume of each cylinder are known with clearance

- Each cylinder should have the same pressure, and they should match the number in the manual. Step 6: Calculate the PSI to compression ratio. Calculate the PSI to compression ratio. For example, if you have a manometer reading of about 15 and your compression ratio is supposed to be 10:1, then your PSI should be 150, or 15×10/1
- Compressor calculations use absolute pressure Absolute pressure = gauge pressure + atmospheric pressure • (100 psig + 14.7 = 114.7 psia) • (200 psig + 14.7 = 214.7 psia) The atmospheric pressure at the test location is not corrected to sea level Compression ratio = absolute discharge pressure divided by absolute suction pressure
- Since Specific heat at constant pressure (Cp) is a function of temperature, you should recheck the Cp values at the outlet of each stage for your gas composition and then recalculate the specific heat ratio at the outlet of each stage as k = Cp/Cv = Cp / (Cp- (8.314 / MW)
- (m3/
- Let's say you are compressing a gas with a ratio of specific heats of 1.3 (see ratio of specific heats box below) from a suction pressure -0.5 psig to a discharge pressure of 35 psig. To calculate the compression ratio, you first must convert both pressures to absolute pressures by adding 14.7 to them and then divide the absolute discharge.
- Modern turbofan engines typically have several stages of compression, the overall pressure ratio is the ratio of the highest pressure to the intake pressure. But the pressure ratios of each compressor can be a different

- imum temperature in the cycle is 300 K, and the exhaust temperature is 750 K. The
- Utilizing this equation, the optimal compressor pressure ratio could be used to calculate maximum engine thrust at altitude. The original compressor pressure ratio was set at 40 which is close to the maximum operation of turbofan engines, however this ratio may not represent an optimum condition for an engine operating at altitude
- imum pressure in the cycle is 4:0 and the maximum cycle temperature is 1200 K. Compressor and turbine isentropic efﬁciencies are 0:85. The compression process occurs in two stages, each having a pressure ratio of 2:0 with intercooling to 300 Kin between. A 75% effective regenerator reduces fuel costs

* It is possible to calculate a density ratio for each level of compressor efficiency at a given pressure ratio*. This calculation says for any given

- compressor cylinder, Pd' is outlet pressure of compressor cylinder and Pd is discharge pressure to the system. Gas compression process in reciprocating compressor can be expressed such in figure 5. In the r is pressure ratio (pd/ps) and c is clearance volume divided by tota
- e the pounds per square a piston produces
- Dialing the pressure down by 25 psig, the plant could save 12.5 percent energy on an annual basis. To calculate the energy savings, use the energy equation below: BHP x .746 x # hours/year x $/kWh . Motor Efficiency. Note that compressors are rated in hp, not kW. To calculate kW, multiply BHP by the constant (.746)
- VUILTeu a) Calculate the stagnation pressure, Po, at station 3 put your aruer in the box kPa [1 mark] Question 2 Intercooled Turt [10 marlu Figure 1 shows a schematic of an Intercooled Turbojet engine that is intended to be operated at Mach 0.694 at ambient pressure of 37.19 kPa and an ambient temperature: 218 K and sound spee 296 mis The engine is fitted with an heat exchanger, depicted at.
- Boost Pressure (Gauge) psi: Intercooler Effectiveness % Intercooler Pressure Drop : psi: Air Filter Restriction : psi: Muffler System Backpressure : psi: Compressor Efficiency % Turbine Efficiency % Exhaust Gas Inlet Temperature : deg F: Turbine Expansion Ratio

- ing an engine's compression ratio is to calculate the volume that can be contained in the engine's cylinder
- This means the GPSA equation is only suitable for lower pressure ratio <1.15 compressor. The higher the pressure ratio, the bigger the errors. In my application, the pressure ratio is 4.6. This means that the GPSA equation will not work precisely. The simulation software like ProII or Hysis and my compressor software give more accurate result
- Centrifugal compressor impellers can be categorized as shrouded or unshrouded (Figure 5), and their blades as two-dimensional or three-dimensional (Figure 6). The type of impeller chosen for a particular application depends on many considerations, such as required operating speed, desired pressure ratio, desired efficiency, and equipment cost
- Clearance 5% of the swept volume Polytropic index n=1.3 Bore-stroke ratio: 2:

Understanding the flow and pressure (a.k.a. cfm and psi) requirements for your facility is key when choosing an air compressor. Pressure and flow are two very common terms used when discussing compressed air systems.. Pressure can be measured in pounds per square inch (psi), or bar (metric measure of pressure) Compressors and pumps, when undergo a steady-flow process, consume power. The isentropic efficiency of a compressor or pump is defined as the ratio of the work input to an isentropic process, to the work input to the actual process between the same inlet and exit pressures. η C = Isentropic compressor (pump) work/Actual compressor (pump) wor To evaluate the performance of an existing compressor, the objective is to calculate the compressor efficiency (η) and power requirement. Known and measured properties are: a. Standard condition gas volume flow rate (q S) or gas mass rate b. Gas composition (z i) c. Suction pressure (P 1) and temperature (T 1) d It is calculated so to distribute the power evenly between stages. The power is proportional to the pressure ratio p out/p in. The pressure is abolute pressure not guage. For example, to achieve 10 bar guage in two stages you first calculate the t..

It takes more power to compress air to a higher pressure. Also, air losses and control-air use increase with pressures within an air compressor so the compressor motor isn't overloaded at higher pressures. For example, the compression module in an 8-bar rotary screw compressor operates at a different speed than in a 10-bar machine calculate it, the ratio itself is independent of pressures. By definition, compression ratio is the ratio of the absolute discharge pressure (psia) to the absolute suction pressure (psia). Absolute pres-sure is defined as the pressure existing above a perfect vacuum. Therefore in the air around us, absolute pressure and atmospheric pressure are. From the definition of enthalpy, calculate the specific work done by knowing the temperature change and the specific heat of the fluid at constant pressure: For an isentropic compressor, Rearrange the above equation to solve for the temperature difference This compression ratio calculator can be used to work out the compression ratio of your engine. How to use: simply fill in all the boxes below with the requested figures and click on Calculate CR to find your engine's compression ratio. Definition of Compression Ratio. The compression ratio of an engine is a very important element in engine performance Compressor Efficiency is the ratio of input kinetic energy to the work done by the compressor is calculated using Compressor efficiency=Kinetic Energy/Work .To calculate Compressor Efficiency, you need Kinetic Energy (KE) and Work (W).With our tool, you need to enter the respective value for Kinetic Energy and Work and hit the calculate button

In this study, various investigations were performed on the reduction of calculation errors of compressor models which can calculate compressor performance (pressure ratio, rotational speed) at an arbitrary operating point. For this purpose, three compressor models, including the Jensen & Kristensen model and the newly modified model, are presented in this study Given a certain engine displacement and certain other factors you can calculate how much boost will be required to achieve a stated level of horsepower. Then it's off to the compressor maps to check airflow v. pressure ratio. In choosing a particular turbo you need to know how many Pounds Per Minute or CFM the turbo compressor map indicates for. Check Out Compressor Pressure on eBay. Fill Your Cart With Color today! Looking For Compressor Pressure? Find It All On eBay with Fast and Free Shipping The pressure ratio in jet engines is the ratio of pressure between the entrance of the compressor and the exit of the compressor

The thermal efficiency in terms of the compressor pressure ratio (PR = p 2 /p 1), which is the parameter commonly used: In general, increasing the pressure ratio is the most direct way to increase the overall thermal efficiency of a Brayton cycle, because the cycle approaches the Carnot cycle Optimum Intermediate Pressure • This can be generalized to more than two stages (z = number of stages, P1 = intake pressure, P2 = final pressure) • For minimum compressor work - Complete intercooling - Same pressure ratio for all stages = = − 1 −

To find the compression ratio (CR) you divide the total swept volume with the total compressed volume. This is how you find out what these totals are: Swept volume = chamber volume + piston volume + gasket volume + clearance volume + cylinder volume Compressed volume = chamber volume + piston volume + gasket volume + clearance volum Now lets consider the volume at a lower than published pressure. As shown it is simply the ratio of gauge pressure + atmospheric divided by the published pressure + atmospheric and then multiply the dividend by the published volume. So as we do the math we solve for 11.04 SCFM @ 60 PSIG from a device that was shown to consume 14 SCFM @ 80 PSIG Compressor map; Turbocharger Compressor Map Calculation. Speed-Wiz can display turbocharger compressor flow maps and calculate flow rates and pressure ratios and plot them on the compressor map. Several compressor maps are included, and it's easy to add your own compressor maps as shown below. As the calculation window is resized, the.

Show that if the clearance ratio of an ideal single stage reciprocating compressor is c that the volumetric efficiency is given by − =1− 1 (1/ n) L H vol p p η c where pL is the inlet pressure and pH the outlet pressure. SOLUTION Swept volume = V1 - V3 Induced volume = V1- V4 Clearance volume = V3 () design Axial flow compressor by using mean line method for a given mass flow rate and required pressure ratio. The parameters determined also include thermodynamic properties of the working fluid, stage efficiency, number of rotor and stator blades, tip and hub diameters, blad

The old texts and literature for compressors used to express the compressor discharge temperature by means of the following equations: T 2 = T 1 * (P 2 / P 1) (k-1) / k ------------- (1) T 2 = T 1 * (P 2 / P 1) (n-1) / n ------------- (2 For a given compressor, such as a 50-hp (37.3kW) one, flow will decrease as pressure increases, and vice versa. Therefore, it's important to purchase a compressor that optimizes flow and pressure. And keep in mind that every 2 psi (0.14 bar) increase in pressure results in 1 percent more energy needed to maintain the same airflow (cfm) Very very much simplified, if you start with your gas going into the compressor at a certain state, pressure, temperature, density and velocity and you measure the outlet pressure, density and velocity, you can calculate what the temperature should be, any amount that the actual outlet temperature is above the calculated is a measure of the compressor inefficiency

Differential Pressure Vs Inlet flow rate. In this curve, the differential pressure indicated in the vertical axis and Inlet Flow rate in the horizontal axis. With an increase in compressor inlet flow rate, the head developed by the compressor start decreases. The compressor develops maximum differential pressure (head) called Surge (3A) The limits of U, Ca and b 1 - b 2 all place limits on the maximum pressure ratio that can be achieved in an axial compressor. Typical examples are U ≈ 350 m/s, Ca = 200 m/s, b 1 - b 2 < 45°. Compressor blades are typically quite thin and are constructed from lightweight metallic alloys such as aluminium and titanium Compression Ratio and Displacement Calculator This simple tool allows you to calculate the STATIC compression ratio of an engine. It will also allow you to calculate the engine displacement in Liters and Cubic Inches. See Below for explanations of the fields required

A Joule Cycle uses a pressure ratio of 8. Calculate the air standard efficiency. The isentropic efficiency of the turbine and compressor are both 90%. The low pressure in the cycle is 120 kPa. The coldest and hottest temperatures in the cycle are 20oC and 1200oC respectively. Calculate the cycle efficiency with friction and deduce the change If you don't know the manufacturer's guidelines regarding the suitable compression for your car's engine, then rely on the compression ratio of your engine (whether petrol or diesel) and add up those numbers. For example in a compression ratio of 14:1 the sum result is 14+1, so 15 should be the pressure value as indicated on the manometer. Air enters the compressor of a simple gas turbine at 14 lbf/in2 and 520 {eq}^ {\circ} {/eq}R. The isentropic efficiencies of the compressor and turbine are 83% and 87%, respectively. The compressor.. Compression Ratio Formula. The following formula can be used to calculate the compression ratio of an engine. CR = [ (PI/4*b^2*s) + Vc ]/Vc. Where CR is the compression ratio ; b is the cylinder bore diameter; s is the stroke length; Vs is the minimum clearance at the end of the compression strok

The condensing temperature can also fluctuate for various reasons. One reason is that suction pressure differences can affect the pressure ratio of the compressor, which leads to an altered condensation pressure, i.e. a different condensation temperature. Other reasons could be changes in the flow or temperature of the cooling water to the. How to calculate and formula for Reducing air pressure form 6 bar to 5 bar in reciprocation air compressor 2 stage 75 KW driving power motor. Pl do needful how to calculate in reduction of Pressure in Reciprocation air compressor Fig 2 shows the **pressures** through a fan, each of which is described below:. Inlet **Pressure**; is the static **pressure** on the inlet side of the fan.This should also include the velocity **pressure** on the inlet side (if known) that is constant and in-line with the fan. You can include this effect if you wish by using the following formula: pᵢ = pᵢ ± ½.v².ρᵢ {use '+' if the direction of.

Take the volume of the tank expressed in cubic feet (calculated in Step 2) and multiply it by the amount of pressure added during the tanks filling cycle in terms of atmospheric pressure (calculated in Step 6). This is the number of cubic feet that your compressor pumps in the time it took for your tank to fill (recorded in Step 4) The compressible Bernoulli equation is: v 2 2 + γ γ − 1 ⋅ P ρ + g ⋅ z = c o n s t a n t v is fluid velocity. γ is the gas's ratio of specific heats, which for air is about 1.4. I'll refer to the γ / (γ − 1) as α, because it's annoying to type otherwise A compressor with a pressure ratio of 8.0 at sea level will have a pressure ratio of 11.1 at an altitude of 3000 meters (pro-vided that the application's operating pressure is unchanged). This affects the efficiency and, consequently, the power requirement. The amount of change is dependent on the type of compressor and the design