Question { Essar, 47236 }

what is npsh and how to calculate it for a centrifugal pump

Answer

NPSH is the acronym of Net Positive Suction Head, there r 2
NPSH one is NPSH(a) and NPSH(r) i.e., NPSH available and
required. Always NPSH(a) should be higher than the NPSH(r)
this NPSH(R) will be determined my the pump manufacturer
itself.

TO calculate NPSH(a)
NPSHa = Atm. pr.acting on the liquid + static head - vapour
pressure of the liquid- pressure
loss in the suction piping - pressure loss due to the
suction strainer.

Question { 8986 }

I have a thermal flask in which i have to fill the boiled
water.
I also have thermocol, saw dust and silver paper.
Now tell me how i have to arrange these material to attain
minimum
heat loss.

Answer

1.Thermal flask,
2.Saw dust,
3.Thermocol,
I think there is no need of silver paper. But as per your
question it cn be used as the last.

Saw dust should be used next to your thermal flask because
it can be tightly packed without air gap than thermocol.

Question { Dr Reddys, 11108 }

Why stainless steel is corrosion resistant?. What is stress
corrosion cracking?.

Answer

Stainless steel is an alloy of iron, chromium and nickel
and the iron also consists of very less amount of carbon
and corrosion is the property of a material regarding with
the percentage of carbon content in the iron so as
mentioned above the carbon content in stainless steel is
very low, So it is corrosion resistent.

Question { Nalco, 13429 }

How evaporation takes place in a cooling tower ?

Answer

In a cooling tower the hot water is sprayed into small
droplets and allowed to flow from the top to the bottom at
the same time due to the contour flow (in natural draft
cooling towers) air is flowing from bottom to top and there
will be a slight pressure difference inside the cooling
tower with regarding to the atm pressure. The air
temperature will be less than the water temperature and the
hot water is cooled by loosing its sensible heat and some
portion of the water is evaporated.

Question { 6766 }

What is the use of white metal?

Answer

White metal is one of the soft material so mostly it is
used as a lining materil in journal bearings and in the
face of thrust pads which are used in thrust bearings in
high speed machines like turbines.

Question { 6766 }

What is the use of white metal?

Answer

White metal is considered as the one of the soft material,
So it is used as a lining material in journal bearings and
in the face of thrust pads in thrust bearings of high speed
machines like turbines.

Question { TCL, 21543 }

What will cause if you run your engine in critical RPM
continuously?

Answer

Strictly no machines are allowed to run continuously in its
critical speed. If it happens according to your question
the vibration of the machine will be more and as a result
there is chance of seveior damages to the machine, and if
any loose fitted particles may also come out of its
position which results in a serious damage to the machine.
and apart from these the bearings will get damaged.