ALLWEILER NTWH Series Thermal Oil Pump | High-Temperature Heat Transfer Medium Circulation

The NTWH series is a horizontal volute centrifugal pump designed specifically for high-temperature heat transfer media within the ALLHEAT® product line of ALLWEILER, Germany. This series is widely applicable to the circulation of various heat transfer media, including mineral oil, synthetic heat transfer oil, and high-temperature hot water, and can withstand media temperatures up to 400°C.

ALLWEILER, a German pump brand with over 150 years of history (now part of the CIRCOR Group), has accumulated profound 

technical expertise in the field of high-temperature heat transfer pumps. The NTWH series and NTT series both belong to the 

ALLHEAT heat transfer pump family. The difference lies in their application: NTWH is the NTWH (series), while NTT is suitable for 

mineral oil-based heat transfer oil applications. NTWH offers greater compatibility, handling mineral oil, synthetic oil, and 

high-temperature hot water simultaneously, thus broadening its application range.

This series of products is widely used in various industrial sectors, including petrochemicals, chemicals, food processing, rubber, 

wood processing, road construction and asphalt, community heating, and shipbuilding and marine engineering.

ALLWEILER NTWH Series Thermal Oil Pump | High-Temperature Heat Transfer Medium Circulation Model Description

The NTWH series adopts the German standard naming system, which can be understood through the following typical model

 examples:

Model Example | Meaning Explanation

NTWH 65-315/11 | Discharge port diameter DN65, impeller diameter 315mm, 11kW motor

Complete Model Example: NTWH 65-250 U5D-W135-42/350

Code Location | Meaning

NTWH Pump Series Code (ALLHEAT NTWH)

65 | Discharge port diameter DN 65 (mm)

250 | Nominal impeller diameter (mm)

U5D | Seal code

W135 | Material code

42/350 | Other configuration parameters (motor/temperature)

Available Specifications (Partial List):

Model | Suction Port Diameter DN | Discharge Port Diameter DN | Impeller Diameter (mm)

NTWH 32-160 | 50 | 32 | 160

NTWH 40-160 | 65 | 40 160

NTWH 40-200 65 40 200

NTWH 50-160 80 50 160

NTWH 50-200 80 50 200

NTWH 65-160 100 65 160

NTWH 65-200 100 65 200

NTWH 65-250 100 65 250

NTWH 65-315 100 65 315

NTWH 80-200 125 80 200

NTWH 80-250 125 80 250

NTWH 100-250 150 100 250

Note: Available from NTWH 32-160 to NTWH More than ten specifications, ranging from 100 to 250, cover application 

scenarios from low to high traffic.

ALLWEILER NTWH Series Thermal Oil Pump | High-Temperature Heat Transfer Medium Core Technical Parameters

Parameter Item Specification Range

Maximum Flow Rate: 1,250 m³/h

Maximum Head: 100 m

Maximum Medium Temperature: 400 °C (Heat Transfer Oil) / 207 °C (High Temperature Hot Water)

Maximum Outlet Pressure: 16 bar (PN 16)

Speed: 2900 rpm / 1450 rpm / Variable Frequency Speed Control (Optional)

Connection Method: Flange Connection (DIN EN 1092 Standard)

Installation Method: Horizontal, Base Mounting

Design Standard: DIN EN 733

Pump Casing Material: Ductile Iron (JS1025 / GGG-40.3)

Impeller Material: Cast Iron (JL1020)

Shaft Material: Chrome Steel (1.4021)

Bearings: SKF Metal Rolling Bearings (Pump End: Medium-Lubricated Sliding Bearing; Drive End: Grease-Lubricated Ball Bearing)

Sealing Type: Single-End Mechanical Seal (Standard) / Tandem Double-End Mechanical Seal (Optional)

Motor Brand: ABB / Siemens / Teco (optional)

ALLWEILER NTWH Series Thermal Oil Pump | High-Temperature Heat Transfer Medium Product Features and Design Advantages

1. Superior High Temperature Resistance

The NTWH series is specifically designed for mineral oils, synthetic heat transfer oils, and high-temperature hot water, withstanding

 media temperatures up to 400°C. Compared to the NTT series (maximum 350°C), NTWH offers superior temperature resistance, 

making it particularly suitable for high-temperature applications with low-viscosity heat transfer media such as synthetic heat

 transfer oils.

2. Air-Cooled Self-Cooling Design, No External Cooling Water Required

Utilizing a natural air-cooled structure, it operates reliably in high-temperature, flexible operating conditions without the need 

for an external cooling water system. This design simplifies installation, significantly reduces operating costs and maintenance 

requirements, and avoids the scaling, clogging, and additional energy consumption problems that can arise from water-cooling

 systems.

3. Optimized Sealing System

Standard Configuration: Single-end mechanical seal + safety stuffing box (with throttling bushing), self-cooling design

Optional Configuration: Tandem double-end mechanical seal, with a thermosiphon system for leak detection and collection, 

enabling predictive maintenance

The double-end sealing solution is particularly suitable for environmentally sensitive and hazardous fluid conditions, effectively 

preventing oxidation deposits and extending seal life.

4. High-Efficiency and Energy-Saving Design

Special hydraulically balanced impeller: Optimizes flow efficiency and reduces axial thrust, minimizing unnecessary energy 

consumption.

Impeller cutting service: Impellers can be precisely cut according to the customer's actual operating point, eliminating redundant

 energy consumption and saving more than 10% energy compared to domestic hot oil pumps.

Optimized thermal barrier design results in almost no wear and minimal heat loss.

5. High Safety and Durability

Rugged pump body structure and high mechanical rigidity design ensure reliable operation even in extreme environments.

Multiple safety features: throttling bushing, high-efficiency insulation layer, and safety throttling ring prevent leakage of toxic

 heat transfer media.

Optimized pump shaft profile design ensures leak-free operation, with a rated pressure up to 25 bar.

Bearings are protected with high-temperature grease, and the pump end media-lubricated sliding bearings can withstand high loads.

6. Easy Maintenance

Back-pull design: Removable bearing bracket allows the entire rotating component (impeller, shaft, bearing, seal) to be extracted 

without removing the pump casing.

Long maintenance intervals: Under continuous operation conditions, even in harsh environments, maintenance intervals typically

 exceed 12 months.

Many ALLWEILER heat transfer pumps have operated continuously for over 20 years without failure.

7. Flexible configuration options:

Optional ATEX explosion-proof type (suitable for hazardous areas)

Optional tandem double-end mechanical seal (suitable for high safety requirements)

Optional DNV-GL certification (naval and marine engineering)

Optional condition monitoring system (e.g., IN-1000) for predictive maintenance

Selectable speed: 2900 rpm / 1450 rpm / variable frequency drive, adaptable to different operating conditions

ALLWEILER NTWH Series Thermal Oil Pump | High-Temperature Heat Transfer Medium Comparison with NTT Series

Comparison Dimensions: NTWH Series vs. NTT Series

Applicable Heat Transfer Medium: Mineral oil + Synthetic oil + High-temperature hot water Mineral oil is the primary medium

Maximum Medium Temperature: 400 °C vs. 350 °C

Maximum Outlet Pressure: 16 bar (optional 25 bar) vs. 16 bar

Sealing Options: Standard single-end face + optional tandem double-end face Standard single-end face is the primary sealing option

Application Flexibility: Higher (synthetic oil/hot water compatible) vs. Standard (mineral oil only)

Selection Tips: If the medium is synthetic heat transfer oil or high-temperature hot water, or the operating temperature exceeds 350°C, 

the NTWH series is recommended. If the medium is conventional mineral oil heat transfer oil and the temperature is ≤350°C, the NTT 

series is sufficient.

ALLWEILER NTWH Series Thermal Oil Pump | High-Temperature Heat Transfer Medium  Core Application Areas

NTWH series thermal oil pumps are widely used in the following industries and scenarios:

Application Areas Typical Scenarios

Heat Transfer Technology: Thermal oil boilers, heat transfer medium circulation systems, waste heat recovery, community heating

Petrochemical Industry: Hydrocarbon preparation, reactor heating, distillation tower reboilers

Chemical Industry: Chemical preparation, hot fluid transportation, polymerization reactions

Plastics/Rubber Industry: Injection molding machines, extruders, vulcanizing machines heat transfer medium circulation

Textile Dyeing and Finishing: Stenter machines, dryers heat transfer oil circulation

Wood Processing: Continuous press (ContiRoll®) heating plate temperature control

Food Industry: Frying equipment, drying equipment hot oil circulation

Road Construction/Asphalt: Asphalt heating and insulation, storage tank circulation

Marine/Ocean Engineering: Marine heat transfer oil systems (DNV-GL certification available)

Applicable Media

Mineral thermal oil, synthetic thermal oil, high-temperature hot water (up to 207°C), other heat transfer fluids