Slam Valve Motor, supplying
efficient steam engines for homeowners and professional solar installers
precautions for steam power systems
power economical, one watt at a time.
Solar power generators
are three main hazards in solar thermal generators. The first
is that the motor and generator are linked by a belt drive, and belt
drive equipment can remove hands and fingers. The danger is
greater than one might think due to the issue of entrapment.
loose article of clothing can be drawn into the belt area by the wind
created by the equipment, and belt can pull the clothing and associated
appendages into the belt/pulley pinch area and remove it in a fraction
of a second. This hazard is present for all belt driven
equipment, not just steam engines. The standard precaution as
mentioned in the air compressor manual is to arrange a guard around the
belt. In this case the easiest guard is to put the generator
motor inside a weather proof box which completely encloses the belt and
motor. The box needs to be vented at the bottom but must be
proof and made of material which can withstand 400 degree F
temperatures. Painted metal enclosures with no grills and no
gaskets are preferred. The enclosure serves to keep hands
from the belt, to protect the insulation and wiring from the elements,
and to protect against the second hazard. Whenever the
is open, it is vital to be sure that the steam system is not
pressurized and that the generator cannot be connected to electricity.
The system should not be tested with the enclosure open.
second hazard of solar generators is a steam system rupture.
steam system contains high pressure steam and liquid water.
the event of a rupture, the water may be projected at high speed
causing burns some distance away. To prevent rupture, first
always use only pipe and fittings rated for steam use at that pressure
and constructed only of a single type of metal. Galvanized
water pipe is generally recommended for steam, however the specs on
exactly what pressure is recommended are a little hard to trace.
Do not use schedule 40 pipe above 400 degrees F (200 psi).
Schedule 80 pipe and fittings are stronger but again the
are hard to find. Never mix metals, this causes rust and
failure. Generally compression fittings use brass so these
not be used with other than brass pipe. Dielectric junctions
don't work at high temperature, so the entire system has to be the same
metal. Never use soldered pipe unless the solder is
copper/phosphorus which is rated for high temperature.
connections are safer. To keep the pipe within its
limits, use an overpressure regulator device on the system.
reduce the impact of a rupture, the entire steam system should be
encased in fiberglass insulation with a rigid outer shell surrounding
it. This includes the steam motor top end. The
must be insulated to work properly, the insulation also serves to
divert water spraying through a rupture and slow it down.
Surrounding the insulation must be a rigid but not airtight
shell. This protects the insulation from weather and provides
additional baffle to slow the flow of steam and water in the event of a
rupture. The shell should be aluminum so as not to be
if heated to boiler temperatures. The shell should be vented
the bottom to prevent rain from entering.
The third hazard of
solar generators is evacuated tube fracture. The inner layer
the tube is above 400 deg F when operating. Imagine a
hitting one of the tubes. Keep the glass from hitting anyone
landing on anything combustible. A metal mesh surrounding the
tube reduces efficiency slightly but improves safety for non rooftop
For vehicle power plants,
sudden loss of power is very dangerous. Steam
rupture should be made extremely unlikely by proper choice of piping
and mounting. Strain relief the pipe connections properly as
motor itself can vibrate relative to the body of the vehicle. Ideally
multiple steam systems in parallel improve safety. As with
solar power plants, keep the steam system well isolated from
people or anything at all combustible. Consider how things
move if the vehicle is in a collision. An overpressure relief valve is
Similar to electric cars, the battery creates a
safety challenge. It needs to be well mounted so as to not
free in a collision. Combustible materials need to be kept
from the battery. This includes asphalt ; the battery must
sit on the road after a collision. The battery needs to be
away from the fuel system. Expect the insulation to fail
collision; the battery needs to be suspended above the road and away
from the passenger compartment and away from any combustible material.