Multiquip MG30M2D - Manual (Page 21)

MAYCO MG-30 PUMP — OPERATION AND PARTS MANUAL — REV. #3 (09/15/11) — PAGE 21
Reducers and unions are available for connecting the various
sizes of hose.
Air Compressor
Your plaster and mortar pump is equipped with a piston type
Quincy Air Compressor , driven by V-belts from the engine.
This air compressor supplies air to the nozzle for spraying of
material.
Factors Affecting Hose Pressure
Stiffness of the mix is the most important factor affecting hose
pressure. There are others, however, that can be equally
important.
1. Hose Length – Pressure varies directly with the length of
the hose. The pump must develop twice as much pressure
with a 100-ft. length of hose as it does with a 50-ft. length.
2. Hose Size – The pressure required to pump material
through a hose varies with the area of the hose. Thus, if the
pressure required for a length of 2-inch diameter (5.08 cm.)
hose is 300 pounds (136 Kg.), the pressure required for
the same length of 1.5-inch diameter (3.81 cm.) hose would
be over 500 pounds (227 Kg.) using the same pumping
rate.
3. Gypsum – In using gypsum plaster a rich mix (such as
2:1) will take more pressure to pump than a leaner mix. In
a 2:1 mix you will probably have to make your mix
somewhat softer than a 3:1 mix.
4. Binders – Some binders for plaster take more pressure
than others. A plaster using gypsum will require the most
pressure. Portland Cement pumps quite easily with a
minimum of pressure, as does clay or lime.
5. Aggregates – The most familiar types of aggregate are
sand , vermiculite , perlite and zonolite . Each one of these
has its own characteristics. As most sand absorbs very
little water, it is the easiest with which to control the
consistency of materials. vermiculite or zonolite, on the
other hand, absorb considerably
more water when pumped
under pressure, as do most perlites. Therefore, in the latter
cases, whether the binder is gypsum or
Portland Cement ,
your mix must be somewhat softer.
MG-30 PUMP — GENERAL INFORMATION
NOTE
All materials being pumped become
stiffer, when applied under pressure.
Therefore, the mix at the machine must
be softer than if it were taken from the
mixer for hand application.
Connecting material hoses by means of
any type of quick coupling device is not
recommended because they generally
do not have an adequate pressure rating
and are hazardous.
NOTE
.
Effect of Hose Pressure On Height
When elevating a plaster containing gypsum and light weight
aggregate add about one-half pound per square inch to the
required horizontal pump pressure for every foot you elevate the
nozzle above the Mayco Model MG-30 plastering unit. This
additional pressure is generally not serious because you will
probably be running between 1 and 2 lbs. per square inch per
foot to overcome friction in the hose.
As an example, if you were using a 40 ft. (12 meters) hose with a
pressure of 1-1/2 psi per foot or a total of 60 psi when plastering
a wall, and you sprayed a 20 ft. (6 meters) ceiling, you would only
increase the pressure 10 lbs. (4.53 Kg.) or have a total of 70 lbs. (32
Kg.) pump pressure. If you wanted to spray a 40 ft. (12 meters)
ceiling and needed another 40 ft. (12 meters) of hose, your pump
pressure would be:
First 40 feet @ 1-1/2 psi/ft. .............60 psi
Second 40 feet@ 1-1/2 psi/ft. ......... 60 psi
Elevation pressure 40 psi/2 ...........20 psi
Total pump pressure .......140 psi
NOTE
Material hose, steel delivery line and
couplings are available in various
pressure ratings when
new . Age
wear and tear will reduce the above
calculated pressure rating.
Nozzle
The MAYCO spray nozzle is constructed of a lightweight material.
It has been designed with a removable cap for changing to various
size orifices and is also equipped with an atomizer for variance
in spray patterns.
The output from the spray nozzle can be controlled to supply a
volume from zero to 4.5 cu. ft. per minute. Because of this
considerable range in volume, the orifice in the nozzle must be
changed to fit the desired volume in order to obtain a good pattern.
In most cases a 5/8-inch (1.58 cm.) orifice will give a good pattern
in most browning or scratching applied to paperback wire. On
metal lath you should use as large an orifice as possible and
lower the air pressure. In most cases the air jet should be set
back from the orifice 1/2 to 5/8 inch (1.27 to 1.58 cm.). You will
find an air valve at the nozzle to control the air pressure.