HAWE overflow valve (Germany)

Brand

HAWE/Germany

Application Areas

Environmental Protection, Food/Agricultural Products, Chemical Industry, Petroleum, Mining

Main Functions of HAWE Relief Valves (Germany):

Constant Pressure Relief: In a fixed-displacement pump throttling system, the pump provides a constant flow rate. When system pressure increases, the flow demand decreases. At this time, the relief valve opens, allowing excess flow to return to the oil tank, ensuring the inlet pressure of the relief valve, i.e., the pump outlet pressure, remains constant (the valve opening fluctuates with pressure).

Pressure Stabilization: The relief valve is connected in series in the return oil line, generating back pressure and increasing the smoothness of moving parts.

System Unloading: A small-flow solenoid valve is connected in series at the remote control port of the relief valve. When the solenoid is energized, the remote control port of the relief valve connects to the oil tank, unloading the hydraulic pump. The relief valve then functions as an unloading valve.

Safety Protection: The valve is closed during normal system operation. The relief valve opens only when the load exceeds the specified limit (system pressure exceeds the set pressure) to provide overload protection and prevent further pressure increase (typically, the set pressure of the relief valve is 10%~20% higher than the system's maximum working pressure).

In practical applications, it is generally used as a unloading valve, a remote pressure regulating valve, a high/low pressure multi-stage control valve, a sequence valve, and to generate back pressure (connected in series in the return oil line).

Relief valves generally have two structures: 1. Direct-acting relief valve. 2. Pilot-operated relief valve.

The main requirements for relief valves are: large pressure regulation range, small pressure regulation deviation, small pressure fluctuation, sensitive action, large overload capacity, and low noise.

Notes on HAWE (Germany) relief valves:

Noise and Vibration

Components in hydraulic systems that are prone to noise are generally considered to be pumps and valves, with relief valves and solenoid directional valves being the main contributors. Many factors contribute to noise generation.

Noise can be categorized into flow velocity noise and mechanical noise. Noise generated by flow velocity is mainly due to oil vibration, cavitation, and hydraulic shock. Noise generated by mechanical means is mainly due to the impact and friction of valve components.

(1) Noise caused by uneven pressure

The pilot valve section is a vibration-prone part, as shown in Figure 3. During overflow under high pressure, the axial opening of the pilot valve is very small, only 0.003~0.006 cm. The flow area is very small, and the flow velocity is very high, reaching 200 m/s, easily causing uneven pressure distribution, resulting in an imbalance of radial force in the cone valve and vibration. In addition, the ellipticity generated during the machining of the cone valve and cone valve seat, dirt adhering to the pilot valve port, and deformation of the pressure regulating spring can also cause cone valve vibration. Therefore, the pilot valve is generally considered the source of noise.

Due to the presence of elastic elements (springs) and moving mass (cone valve), a condition for oscillation is created, and the front cavity of the pilot valve acts as a resonant cavity. Therefore, vibration of the cone valve easily causes resonance of the entire valve, generating noise. Noise is usually accompanied by severe pressure fluctuations. (2) Noise from Cavitation

When air is drawn into the oil for various reasons, or when the oil pressure is lower than atmospheric pressure, some of the air dissolved in the oil will precipitate and form bubbles. These bubbles are larger in low-pressure areas, but when they flow with the oil to high-pressure areas, they are compressed and their volume suddenly decreases or the bubbles disappear; conversely, if the volume is smaller in high-pressure areas, it suddenly increases when flowing to low-pressure areas. This rapid change in the volume of bubbles in the oil generates noise, and because this process occurs instantaneously, it will cause local hydraulic shock and vibration. The pilot valve port and main valve port of a pilot-operated relief valve experience significant changes in oil flow rate and pressure, making cavitation easy to occur, thus generating noise and vibration.

(3) Noise from Hydraulic Shock

When unloading, the German HAWE relief valve will generate pressure shock noise due to the rapid drop in pressure in the hydraulic circuit. The higher the pressure and capacity of the operating conditions, the greater this impact noise. This is because the unloading time of the relief valve is very short, causing hydraulic shock. During unloading, the oil flow rate changes drastically, causing a sudden pressure change and creating a pressure wave impact. The pressure wave is a small shock wave, producing very little noise on its own. However, as it travels through the system with the oil, if it resonates with any mechanical part, it can amplify vibration and increase noise. Therefore, hydraulic shock noise is usually accompanied by system vibration.

(4) Mechanical noise

LHK 40 F-11CPV-350

SC034L

SC034L ISO

SCP-047R-N-DL4-L35-S0S-000

SCP-056R-N-DL4-L35-S0S-000

SCP-064R-N-DL4-L35-S0S-000

SCP-084R-N-DL4-L35-S0S-000

G3-1-G24

GZ3-1-G24

GZ3-1R-G24

GS2-1-G24

GR2-1-G24

GZ4-1-G24

SWPN21-W-X24DC

SWPN21-B-X24DC

DG1RF

R3.6

PMVP5-43 PMVP4-44/G24

EV1M2-12/24

KM7831 010

MVS85E-110

CDK3-5-30

CDK3-2-160

SG 0 R-AK

SG 0 W-CK

RC 1 E

AS2/450-G24

HRP3V

Our company mainly deals in European and American brands and can purchase brands from any European country. For example, our advantageous German brands include: BURKERT, DEMAG, HAWE, REXROTH, HYDAC, PILZ relays, FESTO, IFM sensors, E+H, HEIDENHAIN, P+F sensors, SICK, TURCK, and HIRSCHMANN industrial switches. German brands: Hengstler, Murr, Schmersal, Samson, EPRO (Emerson Group)

American brands: MOOG, ASCO, MAC, NUMATICS, PARKER, VICKERS, ROSS

British brands: Norgren

Italian brands: OMAL, ATOS, CAMOZZI, UNIVER, Camozzi.