16-8
SAND TIMER-harder to make, but more accurate
A sand timer consists of a tube of glass closed
at both ends, with a narrow neck in the middle. It
is partly filled with fine sand. The sand runs from
the upper to the lower half in an exact period of
time.
‘Egg timers’, or 3-minute sand timers, can be
purchased at low cost in some areas. To use
one, count the number of pulses or breaths for
3 minutes and then divide by 3 to know the
number of pulses or breaths per minute.
A 1-minute sand timer can be made as follows:
Store-bought
3-minule sand
timer.
One-minute sand
timer available
through UNICEF
(UNIPAC
#0568500).
I. Heat the middle of
a glass tube over a
Bunscn burner or other
small, very hot flame.
2. Stretch the tube
to make a thin neck
in the middle.
3. Seal one
end of the tube
by melting it
slowly.
4. Wash some fine
sand to remove (he
dirt Dry it in the sun,
and sift it through
a very fine strainer.
Then heat the sand to
remove moisture.
5. Put just enough sand
in the tube so that it
takes exactly 1 minute
for all of it to run from
one pari to the other.
(Use someone’s watch
with a second hand to
check this.)
6. Seal the
other end of
the tube.
Note: Do not be surprised if you have to
make the timer several times before you
get it just right. Try to make sure you have
the right amount of sand before you seal
the tube. If the sand sticks, try to find a
smoother, finer sand, and be sure it is
absolutely dry. Protect the timer by keeping
it in a box with cotton, as it can break very
easily at the neck.
An easier method is to use
a ‘soft glass’ test tube, or
a blood collection tube.
Instead of melting the end,
simply seal it with a cork or
rubber stopper. This timer
may be less accurate in a
moist climate.
Sometimes a timer will get partly clogged and give a false reading. So it is a good
idea to check your timer occasionally (especially the water timer) with someone’s
watch. If this is not possible, you can make 2 timers and check one against the other.
Sand and water timers, if well made, are fairly accurate. They are better than
watches in that health workers, midwives, or almost anyone can learn to make and use
them. A person using them does not need to know how to read a clock.