gears

Pressure – The Inner Working of the Basic Pressure Gauge

Published on May 9, 2018 by Leave a comment

Everyday here at EXAIR we talk about pressure, specifically compressed air pressure. The other day I was looking up our model 9011, 1/4″ NPT Pressure Gauge , and it got me to wondering just how does this small piece of industrial equipment work. The best way to find out is to tear it apart.

Most mechanical gauges utilize a Bourdon-tube. The Bourdon-tube was invented in 1849 by a French watchmaker, Eugéne Bourdon. The movable end of the Bourdon-tube is connected via a pivot pin/link to the lever. The lever is an extension of the sector gear, and movement of the lever results in rotation of the sector gear. The sector gear meshes with a spur gear (not visible) on the indicator needle axle which passes through the gauge face and holds the indicator needle. Lastly, there is a small hair spring in place to put tension on the gear system to eliminate gear lash and hysteresis.

When the pressure inside the Bourdon-tube increases, the Bourdon-tube will straighten. The amount of straightening that occurs is proportional to the pressure inside the tube. As the tube straightens, the movement engages the link, lever and gear system that results in the indicator needle sweeping across the gauge.

The video below shows the application of air pressure to the Bourdon-tube and how it straightens, resulting in movement of the link/lever system, and rotation of the sector gear – resulting in the needle movement.

If you need a pressure gauge or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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EXAIR Atomizing Nozzles in a Forging Plant

Published on September 13, 2016 by johnball2014Leave a comment

A steel forging plant was using a releasing agent in their process. This particular operation was to make a blank gear. It started with a heated ingot that was placed in a two-part dual stamp die. The front section of the die creates the hub of the gear, and the back section would finish the outer diameter of the gear. The operator would use tongs to grab the hot part and place it in the front and back portion of the die. Each time the press would cycle, a release agent would be sprayed onto the die so that the parts would not stick. As you can see in the picture below, they had six liquid spray nozzles modified to spray the entire surface. Two of the spray nozzles were blowing the release agent to the top portion of the die, and four spray nozzles would spray the entire bottom portion of the die. Every time the press would cycle, the release agent would be sprayed.

Forging press with liquid spraying nozzles

At a rate of making a part every six seconds, much release agent was being sprayed. This lubrication for forging was not inexpensive, and it was adding cost to their operation. They called EXAIR to see if we could help in this matter.

The EXAIR Atomizing Nozzles use compressed air to help “shear” the liquid into a very fine mist. The smaller the liquid particle size, the more surface area is created. This is very beneficial in saving liquid material without reducing the required performance. This customer purchased two Internal Mix Narrow Angle Round Pattern Atomizing Nozzles, model AN1040SS to replace the six liquid nozzles that he was using. With a stainless steel construction as standard, it makes the Atomizing Nozzle very corrosion resistant and able to handle 400 deg. F (204 deg. C) temperatures. With the narrow angle round spray pattern, they could position the Atomizing Nozzles to cover the entire top and bottom of the die (reference the photo below). With the liquid adjustment valve, they could dial in just the right amount of release agent to keep the process running smoothly. After the first week in modifying their operation with EXAIR Atomizing Nozzles, they noticed that they were using only half the amount of releasing agent. This helped to cut cost in their operation, increasing their profit margin.

Forging press with EXAIR Atomizing Nozzles

We can spray liquids very economically and efficiently. We have different types of spray patterns for three different styles. We have the Internal Mix style for low viscosity fluids as purchased by the above customer; the External Mix for high viscosity fluids, and the Siphon Fed for unpressurized liquid systems requiring gravity or siphoning. We can atomize liquids up to a rate of 5 gallons per minute (19 liters per minute). If you believe that you are going through too much liquid in your process, you can contact an Application Engineer to see if we have the correct Atomizing Nozzle for you.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

One For The Gearheads

Published on October 8, 2013March 2, 2016 by Lee Evans1 Comment

EXAIR Application Engineers are geeky about compressed air, but there’s a few gearheads at heart among us, too. I’m one of them. Read through my blog below for a dive into my most recent gear-driven fun!

Recently I took on a new project at home. One of my friends called me to tell me about an A4 with a potentially blown motor that might find a happy new home for the right (low) price. Seeing as how I’ve procured many a vehicle in just the same way, I’m always optimistic about these kind of things.

So, I made the trip to look at the A4 and found a clean interior, 80k on the clock, and a no-start condition. After sitting at the dealer for over a month without an accurate diagnosis, the owner had it towed to his house where he put it on the market as-is. Unsure of the problem, but confident I could find and fix whatever is needed, I bought the car.

Cranking the engine (2.8 AHA code) over, I could hear a lack of compression, so I pulled the plugs and confirmed with a gauge. Bank one (cylinders 1-3) had virtually zero compression on any cylinder, and bank two (cylinders 4-6) was perfect. Interesting… My first thought was that there was a timing belt failure and valves were bent when getting readings on bank one. But the perfect readings on bank two made me second guess. Nevertheless, I pulled the front carrier/core support and tore down to the timing belt. Sure enough, the teeth of the belt were chewed off at the crank! But, the story goes on…

The repair in a case like this is to pull the cylinder heads, check all the intake and exhaust valves for leakage, and replace those that are faulty (or all the valves depending on their condition). Some people call this a rebuild of the top half of the engine, which is pretty accurate.

When I removed the cylinder heads and began to disassemble them, I could tell something wasn’t right. There’s a camshaft adjustment unit used to advance or retard valve timing that has a special landing and thread for a service tool. On the bank one cylinder head, this landing was missing (see the photo below). Strange! And, normally, the camshafts can be removed fairly easily once their bearing caps are removed. But, on this cylinder head, no dice.

Ultimately I found that the landing for the camshaft adjustment unit broke off and wedged on the exhaust cam of bank one. See the photos below for the gouge mark on the casting. This cam seized, locked everything on the head, and forced the crank to chew the teeth off the timing belt. Miraculously, the valves on bank two avoided any damage and triple checked out when disassembled.