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MAYCO LS400/LS500 PUMP — OPERATION AND PARTS MANUAL — REV. #6 (09/19/11) — PAGE 33
The use of 2 -1/2” I.D. hose in these extreme cases reduces
line pressures or the addition of slight amounts of water to the
mix, if permissible, will permit easier pumping. The use of
certain pumping admixtures may help.
If excessive pulsation exists in the hose, it is advisable to
use burlap or some means of wear protection under the hose
at points where the hose may wear through the outer cover;
e.g. over forms, steel or sharp curbs.
SNAP-JOINT COUPLINGS
When using Snap-Joint couplings with gaskets to join hose,
see that they are washed clean after each job. Keeping the
hose ends clean (heavy duty) is very important for the best
job setup. A thin coat of grease on the rubber gasket or
dipping both coupling and gasket in water before coupling the
hose will make for easier installation.
NEW PUMPS
All new pumps are ‘water pressure tested” at the factory This
procedure permits a thorough inspection of entire drive
system and valving under simulated full load conditions. The
pump owner can do the same by making an adapter to couple
to the end of the discharge cone: e.g., the use of a standard
2" pipe cap with a 3/8" drilled hole in the center, screwed on
to the end of hinged cone or reducer at the pump.
Fill the hopper with water after making sure that all sand and
rock have been removed from manifold. Operate pump at full
throttle and the 3/8" diameter hole restriction will create
sufficient back pressure to make thorough inspection of all
moving parts.
LS400/LS500 PUMP — PUMPING INFORMATION
THE EFFECTS OF HEAT AND EXCESSIVE
TIME ON CONCRETE:
Hot concrete, commonly referred to as a hot load, is concrete
that has been in the redi-mix truck in excess of 2 to 3 hours.
On a hot day, this amount of time is even less.
A brief explanation of why heat and time affect concrete:
Concrete starts setting by drying up through a chemical
reaction. The catalyst to this reaction is heat. When
pumping a hot load, it is important to remember that
when you have to stop pumping for any reason, add
water to the concrete in the hopper and hand mix and
move concrete in the hose every 5 minutes. If the shut
down time becomes too long, wash out
immediately
.
If it is necessary to wait 1/2 hour or more for another load of
concrete, to prevent setting of the mix in the system, it is
advisable to consider the following factors (
A through
D
)
affecting the concrete:
A. How old is the concrete?
B. Is there an accelerator, calcium chloride, red label,
etc., in the concrete?
C. The temperature of the day, 80, 90, degrees?
D. How much system you have out and how stiff was
the mix you were pumping?
PREVENTING MIX SET-UP AFTER PUMP SHUTDOWN
When the pump is stopped for any reason during a pour; e.g.,
moving hose, waiting for redi-mix truck, the following sugges-
tions are offered:
1. Leave the hopper full of concrete at the time of shutdown.
It is important not to let the
redi-mix
driver wash too
much water into the hopper, as this could cause separa-
tion of the concrete in the hopper.
2. If the
shutdown
period exceeds 2 to 3 minutes, turn off
the engine so the vibration does not separate the mix in
the hopper which can cause a blockage in the manifold
when the pump is started.
3. If it is necessary to wait 10 minutes or more for another
load of concrete, it is wise to start the pump and pump
6 or 8 strokes every 5 minutes to prevent setting of the
mix in the system. If waiting time is excessive, it would
be wise to wash out the pump and hoses and start over
when the new truck arrives.
4. When pumping stiff mixes and there is waiting time
between redi-mix trucks, it is advisable to add some
water to the last hopper of material and “hand mix” to
ensure an easier start with the following load.
5. When the pumping job requires a stiffer mix, the following
method is suggested for starting: Take a water hose with
a nozzle on it and apply water with a fine spray to the
concrete as it comes down the redi-mix chute into the
pump hopper after the slurry procedure is completed and
you are ready to start pumping.