Watson-Marlow 825 - Manual (Page 5)

Watson-Marlow 825 and 840 User Manual 5
7 Recommended operating
procedures
Do keep delivery and suction tubes as short and direct as possible using a minimum
of swept bends
Do use suction and delivery pipes equal to or larger than the bore of the tube in the
pumphead. When pumping viscous fluids, the losses caused by increased friction can
be overcome by using pipe runs with a cross sectional area several times greater
than the pumping element.
Do keep the pumphead track and all moving parts clean and free from contamina-
tion and debris.
The self-priming nature of peristaltic pumps means valves are not required. Any
valves fitted must cause no restriction to flow in the pumping circuit.
If the rotor is run in an anticlockwise direction with both rocker mechanisms
unlocked no tube occlusion will occur. In this case the rocker mechanisms will snap
back from their disengaged position when losing contact with the tubing. No dam-
age to the pumphead action will be caused by this, however it is not advisable to
allow this action to continue for a prolonged procedure.
8 Installation
Site the pump on a flat horizontal surface allowing a free flow of air around the
pump. Ensure there is 1m of straight tubing before the pumphead inlet and dis-
charge ports.
When requested, motors fitted to Watson-Marlow pumps incorporate a thermal pro-
tection switch which may be used to provide indication of an over-temperature con-
dition. Aside from this, a current overload relay should also be fitted to a contact
breaker. Connect the motor in accordance with the wiring diagram which will be
found in the motor terrminal box.
When a thermal protection switch is fitted in the motor, the leads will be found in
the motor terminal box. They should be connected to stop the pump if the switch
operates. The switch will open circuit at an over temperature condition. See picture
for the simplest connection.
All pumps may be fitted with a door indicator switch. This switch is rated 240V 0.5A
AC maximum power load 50W. This switch is not intended as a primary safety
device. Under normal operation the pumphead door is kept closed and this meets all
statutory requirements as a tool lockable fixed guard.
Do not connect the door switch a back up or any other switch gear with the termi-
nal box of an explosion proof motor unless the switch has a suitable Exd rating for
the zone area in which it is to be mounted.