General
The Dickow-Chemical standard pump is a medium duty pump for handling liquids in the chemical and petrochemical industry, in refineries, for heat transfer liquids a.s.o.
Dimensions and performance range are developed in accordance to EN 22858 (ISO 2858). The whole range is so subdivided that for all service conditions the best efficiency is guaranteed. The maximum capacity goes up to 700 m³/h or 3080 US gpm.
With a wide selection of materials and shaft sealing system DICKOW-chemical pumps are suitable to handle nearly all kind of liquids which are usual in the above mentioned industries. For example we call acids, lyes, solvents, hydrocarbons, heat transfer liquids, heavy fuel, liquid sulphur, melted plastics, bitumen a.s.o.
For handling hot water 190°C (375°F), our pump types NHL are available.
Relevant documents on request.
Construction
The DICKOW-Chemical standard pumps type NCL are single-stage, single-flow volute casing pumps in back pull out design, with an end suction flange and a centerline discharge flange. Bearing housing with intermediate casing, shaft sealing and impeller is mounted to one unit.
With the back pull out design unit can be removed without demounting the pipe connections.
If spacer type couplings are used, the driver can also remain bolted on the base plate.
Volute casing
The pump casing of standard design is cast in one piece and foot mounted on the base plate. The casing is sealed to the atmosphere by confined non-asbestos gaskets.
If required, following special designs are available:
Volute casing with heating jacket
Pumps with heating jacket are required if the liquid temperature decreases when flowing through the pump or when the liquid temperature drops below the melting or cristallization point.
For example: Dimethylterephthalat (DMT), sulphuric liquid, etc.
Heating jackets on volute and intermediate casings with welded cover are designed for heating liquids up to 24 bar/350 psi and 220°C/430°F.
Centerline-mounted casing
API 610, 7th edition, requires centerline-mounted pressure casings, if the pumping fluid temperature are 177°C (350°F) or higher. All NCL-types can be delivered with centerline supported pressure casings.
Impeller
Closed impellers are standard in the DICKOW-chemical pumps. Impellers are made in one piece with solid hubs. To minimize the axial load of the bearings, the impellers are fitted with rings on the back and holes to the suction. Impellers are properly statically and dynamically balanced in acc. to API 610 and VDI-standard 2060.
For handling liquids, containing solids such as slurry and suspensions up to discharge 3", the NCLo-type with open impeller is available. NCLo-pumps are fitted with renewable wearing disks to minimize maintenance costs. For discharge sizes 4" and bigger semi open impellers are available.
The overhung mounted impellers are secured on the shaft by means of a key and a cap screw with Heli-Coil insert.
Wear rings
Volute casing and intermediate casing of NCLs-types are both fitted with renewable wear rings held in place by a press fit with locking screws. Additional impeller wear rings available as an option. The running clearances are in accordance with API 610, 7th edition.
Shaft, shaft sleeve
The pump shaft is able to transmit the full driver output and is accurately machined throughout his entire length and is properly finished at the bearing surfaces.
In order to have satisfactory seal performance the shaft diameter and overhung are sized for minimal shaft deflection at the seal faces.
The shaft construction guarantees a critical speed of more than 10% over the maximum operating speed. The connections "can screw - hub" and "hub - shaft sleeve" are sealed by confined gaskets and the pump shaft has no contact to the pump fluid. The shaft sleeve is in accordance with API 610.
Bearing
The pump shaft is carried by generously dimensioned antifriction bearings outside the pumped liquid. The bearings are oil lubricated. The oil level is regulated by constant level oiler.
Double-row angular ball bearings of Conrad-type (no filling slots) on coupling side, roller bearing on pump side. Service life 25000 hours at continuous operation.
Bearing housing
Bearing housings of NCL-pumps are of split design. Therefore, it is possible to supply the pump sided bearing bracket lantern or corrosion resistant material when handling aggressive liquids.
The pump sided radial seal ring located in the bearing bracket lantern is protected by an additional deflector which avoids entrance of leakage from mechanical seal. The bearing bracket lantern is designed as drip pan and provided with leakage connections.
If required, bearing bracket cooling is also available. Cooling jacket complies to API 610.
Interchangeability of spare parts
To have the advantages of a fine subdivided performance range with many pump types without disadvantage of a large spare part stock, the NCL-types are designed in a unit-composed system. Therefore you need for all sizes of pumps only four bearing sizes, four mechanical seal sizes, four shafts a.s.o. Further, many parts in different pump types are similar and interchangeable with another. The possibilities of interchangeability are shown in the following table.
| Allowable casing pressure | ||
|
Type NCLs: |
up to 205°C / 400°F - 22 bar / 320 psi; | up to 350°C / 660°F - 18 bar / 260 psi |
|
Type NCLhu: |
up to 230°C / 445°F - 31 bar / 450 psi; | up to 350°C / 660°F - 20 bar / 290 psi |
|
Type NCLh: |
up to 300°C / 570°F - 25 bar / 365 psi; | up to 350°C / 660°F - 20 bar / 290 psi |
Materials
The following specified materials are standard design. Further materials, specified in API 610, Appendix E are also available.
| Pump type |
NCLs, API class I-1 |
NCLhu, API class S-1 |
NCLh, API class A-7 | |||
| Ext. casing parts | Ductile iron | GGG-40.3 | Cast steel | GS-C 25 | Stainless stell | 1.4408 |
| Impeller | Cast iron | GG-25 | Cast iron | GG-25 | Stainless stell | 1.4408 |
| Intermediate casing | Ductile iron | GGG-40.3 | Cast steel | GS-C 25 | Stainless stell | 1.4408 |
| Shaft | carbon steel | CK 45 | Carbon steel | CK 45 | Carbon steel | CK 45 |
| Shaft sleeve | Stainless steel | 1.4571 | Stainless steel | 1.4571 | Stainless stell | 1.4571 |
| Throat bushing | Cast iron | GG-25 | Cast iron | GG-25 | Stainless stell | 1.4408 |
| Cap screw | Carbon steel | St 60 | Carbon steel | St 60 | Stainless stell | 1.4571 |
| Bearing housing | Cast iron | GG-25 | Cast iron | GG-25 | Cast iron | GG-25 |
| Lantern | Cast iron | GG-25 | Cast iron | GG-25 | Cast iron | GG-25 |
Shaft sealing
Stuffing box Stuffing boxes are fitted with split cages and split stuffing box ring for an easy replacement of packing rings. Internal circulation or external flushing is possible. Other details of stuffing box construction are designed in acc. to API 610. Mechanical seals can be installed in stuffing box champer on site, no re-machining of parts required.
Mechanical seal
DICKOW-chemical standard pumps can be fitted with all kind of mechanical seals such as single, tandem or double seals. Heating or cooling of the seal is possible. Single seals can be equipped with throttle bushings, quench connections or auxiliary stuffing box. Seal glands are fitted with confined non-asbestos gaskets to prevent blow outs. Gland and piping in accordance with API 610.
Mechanical seals for special service conditions
|
Mechanical seal, system DICKOW, bellows type, design N6q with auxialiary stuffing box to handle heat transfer oil with fluid temperature up to 350°C / 660°F in heat transfer plant, API-code USAXX. |
Balanced mechanical seal acc. to DIN 24960 with throttle bushing on atmospheric side, for handling hydrocarbons in refinery service. |
|
Double acting mechanical seal of Tandemarrangement, system DICKOW N9. |
Single acting mechanical seal, system DICKOW N10, cover with heating jacket, for handling Dimethylterephthalate (DMT) in the chemical industry. |
