Hydraulic Tube Flow Rate

Hydraulic tube flow rate refers to the volume of liquid passing through the pipe cross-section per unit time, typically measured in liters per minute (L/min) or cubic meters per second (m³/s). It is a core parameter in hydraulic system design, directly affecting the speed and efficiency of actuators.

Key Factors Influencing Hydraulic Tube Flow Rate

1. Relationship Between Pipe Diameter and Flow Rate

According to the Bernoulli equation, flow rate Q = π × (d/2)² × v (d is the inner diameter, v is the flow rate). For example, a DN15 (16mm inner diameter) steel pipe with a flow rate of 4 m/s has a theoretical flow rate of ≈30 L/min.

2. Fluid Properties

ISO VG46 hydraulic oil has a viscosity of approximately 46 cSt at 40°C. Excessive viscosity can result in a 5%-15% reduction in flow rate (data source: US NFPA standards).

3. Pressure Loss

The formula for flow resistance along the line is ΔP = λ × (L/d) × (ρv²/2), where λ is the friction coefficient. Actual measurements show that a 10-meter-long DN20 hose has a pressure loss of approximately 0.3 MPa at a flow rate of 30 L/min.

Flow Formula for Hydraulic Piping

The formula for calculating flow in hydraulic piping is: Q = V × A, where Q represents the flow rate, V represents the flow velocity, and A represents the pipe cross-sectional area.

This formula indicates that flow rate is directly proportional to the flow velocity and the pipe cross-sectional area. Therefore, when designing and selecting hydraulic piping, it is necessary to appropriately determine the flow velocity and pipe cross-sectional area to achieve the required flow rate.

Comparison of Flow Parameters of Typical Hydraulic Tubes

The following table lists reference flow rates under common operating conditions:

Note: Data is based on ISO 18752, with a safety factor of 1.5.

Hydraulic Tube Flow Chart

Flow Optimization and Troubleshooting

1. Cavitation Control

Maintain suction line flow velocity <1.2 m/s. For example, in a case study on an injection molding machine, increasing the suction line diameter from DN25 to DN32 extended pump life by 40%.

2. Pipe Layout

Avoid sharp 90° bends. Using 45° elbows can reduce local resistance by 60%.

3. Dynamic Response Matching

For high-frequency switching systems, the pressure wave propagation velocity a = √(K/ρ) (K is the fluid bulk modulus) must be calculated. Typically, a for mineral oil is approximately 1400 m/s.

Special Operating Conditions Recommendations

1. High Temperature Environments (>80°C)

Flow rate should be reduced by 10%-20% to compensate for decreased viscosity.

2. High-Pressure Systems (>35MPa)

It is recommended to use multi-layer steel wire spiral hose, which has a burst pressure of up to four times the operating pressure.

Summary

In practical applications, we can use flow formulas and influencing factors to calculate and analyze hydraulic system flow based on specific requirements and conditions. Understanding basic information and calculation methods for hydraulic tube flow is crucial for understanding and controlling hydraulic system operation. By rationally selecting and designing pipeline specifications, controlling pressure differentials, and choosing the right hydraulic oil, we can ensure efficient and stable hydraulic system operation.

Read more: Relationship Between Hydraulic Tube Diameter And Flow Rate