How does a counter balance valve work?
Counterbalance valves are hydraulic devices that function using this basic principle: fluid can freely flow through a check valve into the actuator, and reverse flow will be blocked using a relief valve until a pre-set pressure is reached that is set based on the system pressure and load capability.
How do you adjust a counter balance valve?
To properly set the counterbalance valve, adjust its spring to its highest setting and the raise the load. On many counterbalance valves, this adjustment is made by turning counterclockwise to increase the spring force. Next, very slowly turn the adjustment in the opposite direction.
Which type of valve is counter balance valve?
Counterbalance valves are also known as load holding valves because of its ability to safely hold heavy loads. The load holding capacity is achieved by allowing free flow into the cylinder/actuator and by blocking the reverse flow until a pilot pressure inversely proportional to the load is applied.
How do you check a counter balance valve?
First the valve is set to just crack open at the desired setting. The pressure is dropped to zero and then brought up to 85% of the setting. The valve is then piloted open and allowed to reseat. At this point the leakage rate must be less than 5 drops per minute.
What is a pneumatic shuttle valve?
A shuttle valve, also known as a double-check valve, allows pressure in a line to be obtained from alternative sources. It is primarily a pneumatic device and is rarely found in hydraulic circuits.
What is a counterbalance cartridge?
Counterbalance valves are used to prevent oil from leaving a cylinder that is holding a load. The counterbalance valve spool and check valve are closed which prevents oil flow out of the cylinder rod, thus preventing the load from lowering. …
What is the difference between pilot operated and direct operated?
The main difference between direct acting and pilot solenoids is that direct-acting solenoid valves have a direct connection with the opening and closing armature, whereas pilot-operated valves employ the use of the process fluid to assist in piloting the operation of the valve.
Why use a pilot operated relief valve?
Like other pressure relief valves (PRV), pilot-operated relief valves (PORV) are used for emergency relief during overpressure events (e.g., a tank gets too hot and the expanding fluid increases the pressure to dangerous levels).
Which valve is used in shuttle valve?
Control Valves A shuttle valve, also known as a double-check valve, allows pressure in a line to be obtained from alternative sources. It is primarily a pneumatic device and is rarely found in hydraulic circuits. Construction is very simple and consists of a ball inside a cylinder, as shown in Figure 4.25a.
Why use a pilot-operated relief valve?
What is a counterbalance valve?
A counterbalance, or load-holding, valve is a mechanism typically located near the actuator that uses hydraulic pressure to keep a load from moving. Generally, these valves have three related functions: support, control and safety. When required for load support, these valves prevent a hydraulic actuator under load from drifting in position.
Are pilot operated check valves better than counterbalances valves?
So, in summary, for simple load-holding applications, the pilot-operated check valve is suitable and more economical. For load-holding and motion control, a counterbalance valve is the answer and worth the extra cost. And couple design advises for both Pilot Operated Check Valves and Counterbalances Valves:
What is a Monday-morning valve?
Also known as Monday-morning valves, these valves slowly introduce pressure to reduce surge damage during start- up. Also known as Monday-morning valves, these valves slowly introduce pressure to reduce surge damage during start- up. Maintain a fixed flow rate even if pressure changes in the system. Adjust the flow rate as needed.
How do airflow control valves work?
Also known as solenoid valves, these valves are operated by an electrical signal to turn airflow on or off. Turn airflow on and off with your foot to keep your hands free to perform other tasks. Also known as air fuses, these valves close automatically to turn airflow off when air volume exceeds the shut-off flow rate.