Nikkiso’s non-seal pumps have no shaft seals; the canned motor and pump are integrated into one housing. The stator has a two-layer structure, consisting of the stator liner, stator band, and extremely tight terminal plate, allowing for a higher degree of safety. With the pressure raised by the impeller, the liquid is sent to the discharge side. Some of the liquid is also sent to the motor to lubricate bearings and cool the motor, then it is returned to the suction side through the vents on the shaft (regular model).
Basic Type (N Type)
The pump and motor are connected by an adapter plate or a FB housing. A portion of the liquid being handled is taken from the impeller outlet part of the pump chamber into the rotor chamber for the purposes of cooling the motor and lubricating the bearings and returned to the pump chamber through the hollow shaft.
A jacket may be fitted to the outer wall of the stator assembly depending on the temperature and other characteristics of the liquid being pumped.
Circulation Boost Basic Type (V Type)
The cross-sectional dimensions are the same as those of the basic type (N type), but the return passage is wider to maintain a return flow of liquid when handling high-viscosity liquids.
High Temperature Type (T Type)
The pump and motor are connected by an adaptor. The adaptor separates thermally the pump from the motor and prevents heat transfer from the pump to the motor. In the High Temperature Type, an independent circulating system is provided for cooling the motor and lubricating the bearings.
Circulation is effected by the auxiliary impeller located at the fore end of the rotor chamber. A heat exchanger is fitted to the outer wall of the stator assembly to cool the circulation liquid.
Type HX: High Temperature liquid Handling Type without cooling
The type HX is designed for high temperature liquid handling without any cooling by adopting special ceramic motor insulation.
Type HX can be installed heating Jacket and well suited for handling high melting point liquids (above 140degC) which exceed the temperature limit of normal organic motor insulation materials.
Slurry Handling Type (S, M, G Type)
The basic construction is identical with that of the High-Temperature Type. The function of this arrangement is to prevent the slurry handled from entering into the rotor chamber.
Clean compatible liquid with the liquid handled is flushed from the inlet port established at the rear of the motor to prevent slurry from entering into the rotor chamber, for which back flushing line would have to be established.
See Fig. 4-2 for the amount of liquid used for back flushing.
Slurry Handling Type with a Mechanical Seal (M Type)
In response to the necessity of decreasing a back flushing volume, a type incorporating a mechanical seal between the pump and motor is also available. (See Fig. 1-5)
Such type is called a Slurry Handling Type with a Mechanical Seal (M Type). The back flushing volume can be decreased up to 100 ml/day to 500 ml/d. (See Fig. 4-2)
Gas Seal Slurry Handling Type (G Type)
A gas seal type is also available which is suitable for handling heavily corrosive liquid, liquid liable to polymerize or highly concentrated slurry liquid. (See Fig. 1-6) The construction is basically identical with that of the above Slurry Handling Type with a Mechanical Seal and the feature of this type is that a gas chamber has been installed between the pump unit and motor unit.
The pump unit has totally been separated from the motor unit with the gas chamber, thus banishing a fear of the mechanical seal wearing out or corroding by handled liquid.
As the back flushing liquid (100 ml/day to 500 ml/day), clean mother liquid or clean liquid permitted to get mixed in the handled liquid if only being a very small quantity may be used. Also, as a gas charged in the gas seal chamber, for example, air on N2 can be used. (See Fig. 4-3)
High Melting Point Type (B & C Types)
This pump has a construction suitable for handling liquid with a high solidifying point. This pump is provided with a heating jacket on the outer face of the pump and the motor to prevent liquid from solidifying at a time of the liquid filling and during the pump operation. According to the solidifying point of the liquid and the liquid temperature, a Simple High Melting Point Type (C Type) and a Complete High Melting Point Type (B Type) may be used with a proper selection.
Reverse Circulation Type (Q Type)
The feature of this pump is that the circulation line does not form a closed circuit.
The circulation liquid passes through the front bearing housing from the impeller outlet part of the pump volute chamber into the rotor chamber, passes through the rotor chamber and after being extracted from the outlet of the rear bearing housing at the rear of the motor is returned to the vapour zone in the suction tank through the reverse circulation line. (See Fig. 4-4)
With the basic type, in case of liquid which vaporizes easily, if the temperature of the circulation liquid rises even slightly, the liquid will vaporize when it passes through the rotor chamber and result in cavitation, etc.
Self-priming Horizontal Type (DN Type)
The basic construction is identical with that of the Basic Type and this type has been so built as to allow a self-priming with no flap valve provided.
Since there is no flap valve, heavily corrosive liquid can also be handled and further, there is no possibility of a poor self-priming due to clogging in the flap valve.
Type HK: Low Flow & Higher Head, High speed
The type HK is designed for handling easily evaporating liquid without auxiliary piping of reverse circulation line. This pump can be maintained higher pressure than vapor pressure in motor chamber and prevent the evaporation. It would be advisable to consult Nikkiso Co., Ltd. if you consider type HK.