# Search results

1. ### Measurement points for fan performance curve

Volume. Should turbulence in some points of the duct add some dynamics to static pressure being measured by the probe placed right perpendicular to flow ?
2. ### Measurement points for fan performance curve

For finding fan performance curve where better to put static pressure probes - near the surface or near the center of the duct ?
3. ### The capillary action's limit

: ".........venerable question of why sap rises in tall trees [32]. We hope to address this problem in future work"

5. ### Oil boiling point at vacuum

Millitorrs are generally called "microns". It is assumed among refrigeration engineers that during vacuumation processes the oils in systems worked upon, themselves, do not boil - no matter how high vacuum would be achieved. I am in doubt.
6. ### The capillary action's limit

I meant artificial material.
7. ### The capillary action's limit

Is it feasable to achieve elavation of water to, let's say, 10 m height due to the capillary action effect ? Or the capillary diameter for that to achieve should be less than the water molecules themselves ?
8. ### Oil boiling point at vacuum

What may be the boiling point (temperature) of a refrigeration POE oil at, let's say, 500 microns absolute pressure ?
9. ### Ac lagging

You are correct. It is always assumed so as you say, but in reality the "loss in copper" current starts immediately the emf is applied. What is form of the current on oscilloscope ? (I have never had an access to one) A slope of the resistive current, then the sine of the magnetizing current...

Thank you !
11. ### Ac lagging

Roughly speaking, a generator's rotor pole passing the stator pole will indeed cause no current in a (load) coil so far the poles have not passed over their midpoint ? No matter how slow moves the rotor ?
12. ### Ac lagging

AC, as is known, "lags" voltage in a coil and we are familiar with the drawings of the two sine waves with the 90 degree angular "shift" between them. For 50 Hz the shift translates into 5 µs "lagging" but, for instance, for 0.05 Hz AC it would indeed be 5 s ? What I mean : frequency does not...
13. ### Gas density at vacuum

It seems the gas density is related to the gas residue in the vacuum % found from a Vacuum Conversion Table. PS. Preconcern was vacuumation of systems and knowledge of how much actually there is left in a system - especially water - at different vacuum degrees.
14. ### Gas density at vacuum

Hello Nasu Water may turn to ice and stay in the container - but we can add heat and not let the water to turn to ice. What else may prevent different particles be removed proportionally - both to each other and to the pressure decreasing ?
15. ### Gas density at vacuum

Thank you Nasu and Sophiecentaur !
16. ### Gas density at vacuum

A citation: "Boyle's Law: Doubling the pressure on a gas halves its volume, as long as the temperature of the gas and the amount of gas aren't changed." My qwestion: Halving the pressure on a gas , as long as the temperature of the gas and the voulume of gas aren't changed, does halve its...
17. ### Gas density at vacuum

(the scenario is - vacuumating a hermetic container) So, is it right: 1 kg/m3 at 1 BarA, 0.1kg/m3 at 0.1 BarA, ... 0.0001 kg/m3 at 0.0001 BarA ....?
18. ### Gas density at vacuum

Hello! (The water as it is present in the air around us. ) What will be the mass of the air - the above 1 kg - reduced to when we vacuumed the container down to 0.1 bars absolute ?
19. ### Gas density at vacuum

What is the formula to calculate gas (air) density at negative pressures, as well as water content ? For instance, a vessel with air with volume of 1 m3, density 1 kg/m3, and water content 10g /m3 get vacuumed from 1BarA to 0.1BarA isothermally.