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How to Select, Design, and Install O-Ring Seals

Very good and interesting video about O-rings from Tarkka

Video description:

O-rings are the epitome of elegant engineering: The ring itself costs only a few cents, and the groove it goes in is simple and easy to manufacture. But despite this simplicity, the resulting seal is able to reliably hold many thousands of psi of pressure. O-rings are definitely a machine design component you’ll want to be familiar with, and in this video, we’re going to tell you all about how to design seals with them

What is a proportional control valve?

Proportional control valves provide variable hydraulic outputs proportional to an electric input signal in direction, flow or pressure. Electromagnetic output force of the solenoid is proportional to the current flowing through the coil.

Proportional control valves are used in a variety of applications to control the flow or pressure of fluids. Proportional valves are used in a variety of applications, such as controlling the flow or pressure of fluids. A proportional valve can be either directional or non-directional. Proportional valves are widely used in hydraulic systems and produce variable hydraulic outputs proportional to an electric input signal in direction, flow or pressure. .In hydraulic systems, a proportional valve consists of an actuator and a two-port or three-port valve.

A proportional valve is a valve that regulates the flow of fluid based on some input signal. A proportional valve consists of an actuator and a two-port or three-port valve. The actuator is usually a piston or diaphragm with a rod attached to it. The rod is connected to the stem at one end and pivots in the center of the two-port or three-port.

A proportional control valve is a type of valve that can be used to control the flow of a fluid by using an electric input signal. The electric current is converted into a magnetic field which interacts with the coiled wire in the valve, which in turn changes the flow and pressure of the fluid. There are many different types of proportional valves, but they all function in this same way.

SUN cartridges and low temperatures

Recently we got a request from the customer to check the system components to work in a low-temperature environment up to -40°C. Most components in the customer’s system were SUN cartridges.

And I was really surprised by the mess of info on the Sun Hydraulic website about seals that SUN uses in their cartridges.

For example, on the “Seals: Materials of Construction” page you can find the manufacturer’s temperature range: from -22° to 230° F (-30° to 110° C) for Buna N (Nitrile) and -22 to 260° F (-30 to 125°C) for Polyurethane O-rings.

But, if you download Technical Product Information PDF from their library, you can find different temperature range for Buna N: -50°F to 200°F which means -45°C..+93°C and no info about Polyurethane O-rings.

This is why I was confused and had a lot of questions to SUN:

1. Why the different info is provided on SUN website?
2. Why there isn’t a choice for Polyurethane O-rings in seal material when selecting cartridges in the SUN catalog?
3. Why SUN has so high temperatures for the low environment for both Buna N and Polyurethane seals?

Really, all competitors have better low-temperature limits for their cartridges, for example:

– Parker’s Nitrile: from -40°C to +93.3°C
– Danfoss/Comatrol, Buna-N: from -40°C
– Bucher, Buna “N”: from -40°C to +120°C
– Doering, Buna N: from -42.7°C to +93.3°C
– Eaton, Buna N: from -40°C to +120°C
– Hydraforce’ Buna “N”: -40°C to +100°C; polyurethane: -54°C to +107°C.

Because it was critical for my application, I have sent a request directly to SUN to get answers to the questions above and have gotten next response: the correct low work temperature for Buna N is -30°C. Сoncerning the polyurethane seals – this is not a standard option, but any cartridge can be assembled with polyurethane o-rings that provides low temperature rate to -40°C. Not a big difference in the price, but because this is going to be a custom modification the delivery time for cartridges (statement on November 2021) is 15..16 weeks (what actually is not bad for SUN).

Just would like to share this experience with you…

Accumulators sizing for energy storage apps.

This week I worked on an accumulator sizing calculator for BOPs, so I have recovered my thermodynamic knowledge and just would like to note somewhere the materials summary and my thoughts about generic accumulator sizing for energy storage applications.

Let’s get generic formula

First of all, all accumulator calculations based on a generic formula of the polytropic process (Ideal Gas Law):

##pV^{n}=const \hspace{35pt} (1)##

Where the specific value of #n# corresponds to particular cases:
#n=0# for isobaric process
#n=+\infty# for isochoric process
#n=1# for isothermal process
#n=\gamma# for adiabatic process

Now, take a look at the image and apply this formula for the accumulator’s 3 major work stages:

Sizing Accumulators

Sizing Accumulators