Pressure Rating of Internal Gear Pump
Pressure Rating: Definition and Its Role in Internal Gear Pump Selection
Definition:
Pressure Rating refers to the maximum system pressure a hydraulic pump can safely withstand under continuous or intermittent operation, categorized into:
Rated Pressure: Maximum sustained pressure for long-term operation (e.g., >1 minute).
Peak Pressure: Short-term allowable pressure (typically ≤1~2 seconds); exceeding it may cause seal failure or structural damage.
Importance in Pump Selection:
System Compatibility: The rated pressure must exceed the actual system pressure (with 10~20% margin) to prevent overload.
Efficiency & Lifespan: Operating within the rated pressure ensures optimal volumetric efficiency (e.g., >90%) and service life (e.g., 10,000+ hours).
Safety Margin: For high-pressure applications (e.g., construction machinery), the pump’s peak rating must cover hydraulic shocks (e.g., pressure spikes from valve closures).
Material & Seal Design: High-pressure pumps require reinforced housings (e.g., cast iron/steel) and seals (e.g., PTFE or metal-face seals).
How To Optimize The Performance Of Internal Hydraulic Gear Pump
The displacement range of internal gear pumps usually ranges from tens of cubic centimeters per revolution (cm³/rev) to hundreds of cubic centimeters per revolution. For example, the displacement range of Turolla brand internal gear pumps is about 20 cm³/rev to 250 cm³/rev.
Higher pressure rating usually limit the maximum displacement of the pump. Because as the displacement increases, the gear size and clearance inside the pump increase, the sealing and structural strength requirements under high pressure are higher, and the design difficulty and manufacturing cost also increase accordingly.
High-pressure internal gear pumps generally adopt a smaller displacement design to ensure structural strength and sealing performance. The common continuous working pressure can reach 250 bar (about 25 MPa), while low-pressure pumps can be designed with a larger displacement to meet flow requirements.
Industry data shows that the pressure level of internal gear pumps has gradually increased from less than 10 MPa to 20 MPa and even more than 30 MPa, which has promoted the development of small and medium-displacement high-pressure pumps.
The speed range is closely related to the pressure level. Under high pressure conditions, in order to ensure the life and reliability of the pump, the maximum speed must be limited, and the minimum operating speed must be increased to reduce leakage and wear.
For example, the maximum speed of Turolla internal gear pumps at rated pressure is usually between 2000 and 3400 rpm, and as the pressure increases, the minimum operating speed also increases accordingly.
Dorninger Hytronics’ internal gear pump data shows that when the rated pressure is about 160-250 bar, the speed range is generally 100-3400 rpm, and the maximum speed of high-pressure models is lower to ensure the mechanical strength and sealing performance of the pump.
Excessive speed under high pressure will cause increased internal leakage and mechanical wear of the pump, affecting the efficiency and life of the pump.
Matching system pressure and flow requirements: Rationally select the displacement corresponding to the pressure rating to avoid over-design or under-design, and reduce procurement and maintenance costs.
Pay attention to speed adaptability: Ensure that the pump speed range matches the system drive equipment to avoid inefficiency or mechanical failure caused by speed mismatch.
Refer to authoritative brands and parameters: Give priority to brand products with clear pressure rating and performance parameters, such as Turolla, Dorninger, etc., to improve the scientificity and reliability of procurement decisions.
Match The Right Models
Single Gear Pump For KOMATSU PC75UU-2 Excavator
Triple Gear Pump For KOMATSU 3-5 Ton Excavator
Triple Gear Pump For KOMATSU 3-5 Ton Excavator
Internal Gear Pump Pressure Rating Guide: How to Select the Right Pump For Your Machine?
Selecting the right pressure rating for your internal gear pump is critical for optimal hydraulic system performance.
Low-pressure models (10-25 bar): Ideal for lubrication and fuel transfer, featuring high displacement (up to 200 cm³/rev) and speed (4000 rpm)
High-pressure versions (100-250 bar): Engineered for construction equipment and aerospace, with reinforced structures for pressure endurance
Unsure which pressure rating suits your application? This guide examines real-world cases from Bosch Rexroth, Eaton and other top brands to simplify your pump selection process.
Pressure Rating: 10-25 bar (145-362 psi)Petrochemical Industry - fuel delivery system
Provide stable flow (5-50 cm³/rev) and 1.5-2.5 bar working pressure in the fuel delivery pipeline to ensure pulse-free transmission.
Pressure Rating: 10-25 bar (145-362 psi)Food Industry - syrup delivery pump
Using 316 stainless steel, it delivers high-viscosity liquids (such as chocolate sauce) at a pressure of 10-15 bar, and the speed is controlled below 2000 rpm to prevent shear denaturation.
Pressure Rating: 25-100 bar (362-1450 psi)Plastics Machinery - injection molding machine clamping unit
Provide high torque (displacement 80 cm³/rev) under 80-100 bar high pressure, clamping force can reach 5000 tons.
Pressure Rating: 25-100 bar (362-1450 psi)Construction Equipment - excavator travel motor drive
Under variable load conditions (25-60 bar fluctuations), the flow is automatically adjusted through the pressure compensation valve (such as Parker T6 series).
Pressure Rating: 100-250 bar (1450-3625 psi)Aerospace Hydraulic - rudder control actuator
Achieve 1-5 cm³/rev micro displacement control under 180-210 bar high pressure, response time <50ms.
Pressure Rating: 100-250 bar (1450-3625 psi)Energy Sector - wind power pitch system
Maintain 160-200 bar working pressure in extreme environments (-40℃~120℃), displacement 20 cm³/rev.
Pressure Rating: 250-400 bar (3625-5800 psi)Oil Industry - deep-sea blowout preventer control
Provide 5-10 cm³/rev precise flow at 300-350 bar pressure to control emergency closure of blowout preventer gate (response time <3 seconds).
Pressure Rating: 250-400 bar (3625-5800 psi)Specialty Forming Presses - isostatic press
Continuously output 400 bar constant pressure (displacement 15 cm³/rev), pressure fluctuation ≤±0.2%
How To Choose the Appropriate Pressure Rating Based On Equipment Requirements?
Identify Maximum System Operating Pressure
The maximum operating pressure defined by the equipment or system conditions is the primary basis for selecting the pressure rating. The pump’s pressure rating should exceed the system’s maximum pressure, typically with a 10%-20% safety margin. Common pressure ratings include D (10 MPa), E (16 MPa), F (20 MPa), and G (25 MPa).
Refer to Authoritative Product Specifications
For example, the LXPG3H series offers rated pressures up to 250 bar (25 MPa) and peak pressures of 330 bar, suitable for high-pressure applications like injection molding and hydraulic presses. Bosch Rexroth’s PGH series can handle up to 350 bar, ideal for heavy-duty industrial equipment.
Match Displacement and Speed Requirements
Higher pressure ratings usually correspond to medium or small displacement designs and impose speed limits. Using pumps with excessive displacement or speed under high pressure increases wear and leakage, reducing service life. Proper matching of pressure rating, displacement, and speed ensures system efficiency and pump longevity.
Consider Application Scenarios and Maintenance Costs
Different industries demand varying pressure levels; construction machinery and automation require high pressure for stable power output, while light industries may opt for lower pressure to reduce costs. Correct selection helps lower maintenance frequency and spare parts expenses, enhancing reliability.
Consult Manufacturers and Technical Experts
For complex conditions, provide pump selection criteria to manufacturers for professional recommendations, avoiding underperformance or overdesign.
FAQs
Internal gear pumps typically have pressure ratings ranging from 10 MPa to 35 MPa. For example, Bosch Rexroth’s PGH series offers rated pressures up to 250 bar (25 MPa) and peak pressures up to 350 bar (35 MPa). High-pressure models are widely used in plastics machinery and die-casting industries.
Higher pressure ratings usually correspond to smaller maximum displacement and limited speed ranges. High-pressure pumps typically have medium to small displacements and maximum speeds controlled below 3000 rpm to ensure sealing and mechanical integrity.
Selection should be based on maximum system operating pressure, peak pressure, and safety margin. It is recommended to choose a pressure rating 10%-20% higher than the system’s maximum pressure to ensure long-term stable and safe operation.
Internal gear pumps feature compact structure, low flow pulsation (~2%-3%), low noise, and high efficiency, making them suitable for high-pressure conditions, servo energy-saving systems, and heavy-duty industrial equipment.
Yes, higher pressure ratings increase design complexity, manufacturing costs, and sealing/material requirements, leading to higher maintenance expenses. Buyers should balance pressure needs and cost-effectiveness to avoid overdesign.
An appropriate pressure rating ensures safe pump operation under maximum system pressure, preventing pump body failure, seal damage, and leakage, thereby safeguarding overall hydraulic system safety and reliability.
Buyers should consider equipment conditions, flow and speed requirements, and reference authoritative brand specs (e.g., Bosch Rexroth, Keda) to select models with matched pressure ratings and high cost-performance, reducing maintenance risks and operational costs.
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