Gas-charged hydraulic accumulators are extremely common in most modern hydraulic systems. They have a variety of functional capabilities, including storing energy, thermal compensation, addressing leakage issues, shock absorption and energy recovery.
There are many advantages associated with the use of hydraulic accumulators, and in many cases you can use them for years without experiencing any significant maintenance issues. However, it is still important to engage in some routine checks and preventative maintenance to reduce the likelihood of such problems occurring.
Here’s an overview of the various types of hydraulic accumulators and what you can do to keep them in shape when working with a hydraulic repair service in Minnesota.
Types of accumulators
There are three main types of gas-charged hydraulic accumulators you’ll find on hydraulic systems: bladder, piston and diaphragm accumulators.
Bladder accumulators are the most popular choice. They feature fast response times (less than 25 milliseconds on average), a maximum gas compression ratio of approximately 4:1 and maximum flow rates of 15 liters per second. There are also high-flow variations of these accumulators that deliver up to 38 liters per second. Bladder accumulators are also known for their outstanding dirt tolerance.
Piston accumulators have much higher gas compression ratios (10:1 in some cases) and flow rates (up to 215 liters per second). Whereas bladder accumulators are mounted in a vertical position to prevent fluid from getting trapped between the shell and bladder, piston accumulators can be mounted in any position, making them slightly more versatile.
Diaphragm accumulators have many of the same advantages of bladder accumulators, but have a higher gas compression ratio (up to 8:1). They have smaller volume limitations, and performance can occasionally be lessened by gas permeation.
There are several things you can do with your hydraulic accumulators to make sure they stay in good condition for longer usage.
For example, when you’re charging the gas end of a diaphragm or bladder accumulator, it’s important to let the nitrogen gas in very slowly. If you have high-pressure nitrogen that expands quickly as it enters the bladder, there’s the possibility that it will chill the polymeric material in the bladder to the extent that there will be immediate, significant brittle failure. Fast pre-charging can also cause the bladder to be shoved underneath the poppet on the same end as the oil, which could result in lacerations to the bladder.
Low pre-charge or lack of pre-charge entirely can also result in some severe consequences for bladder accumulators. The bladder could be crushed into the top of the shell by system pressure, causing it to be punctured by the gas valve. If this happens, only a single cycle would be needed to fully destroy the bladder.
These are just a few of the maintenance issues you need to be aware of when working with the various types of hydraulic accumulators. For more information about hydraulic maintenance, or to schedule an appointment for hydraulic repair service in Minnesota, reach out to M & M Hydraulic Company and we’ll be happy to answer your questions.