Multiquip LS-50TD - Manual (Page 33)

MAYCO LS-40D/LS-40TD/LS-50TD PUMP — OPERATION AND PARTS MANUAL — REV. #11 (09/16/11) — PAGE 33
LS-40D/LS-40TD/LS-50TD PUMP — OPERATING PROCEDURES
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?
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.
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.
Using this procedure will make it easier to pump through
the clean hose. Note: Once the concrete has reached the
end of the hose, do not apply any more water in this
manner as this procedure is used for starting only.
6. Hose sizing is very important: We strongly recommend
on harsh mixes, vertical pushes, stiff concrete, shotcrete,
long pushes, that a 2 -1/2” line be used as far as possible.
The advantages of using the 2 -1/2” line are improved
pumpability, less pumping pressure and less wear on the
pump.
7. Following the pump operation, proper wash out of all
materials or “build-up” within the pump manifold and
hoses will prevent problems when starting the next job.
8. A thorough inspection of the drive components and
greasing of all bearings after each job will ensure ad-
equate lubrication and service to the pump which is
normally operating in wet, gritty conditions.
Over-greasing any bearing on your Mayco
pump will not damage the bearing.