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Encole Sight Glass

Posted by on 19th May 2013

It goes something like this. A request for quotation comes via our automated email. It gets forwarded to an engineer and our purchasing agent. Before the purchasing agent can quote, the engineer has to design the sight glass. Time goes by. Effort is spent by the engineer to actually design to the specification and forward the manufacturing drawings to the purchasing agent who forwards them to the appropriate metal shop or sapphire vendor or quartz vendor. More time goes by. Only the most persistent customers stick around to wait for our quote. At the end of all of this we send the customer our beautiful drawings, and a reasonable quote. Most times we never hear back until weeks, sometimes months later. When we do hear back, it’s usually a purchase order on the project we have already forgotten about. Luckily we have created a mini ERP system (enterprise resource planning) where all that work we did a few months ago gets filed and can be easily retrieved to process the order. The best part of this process, is that all the custom engineering work has been done back then. All we do at this point is send the customer an invoice and start the fabrication. This is where the business of being in business happens. We’ve done our time engineering and manufacturing all kinds of machinery for all kinds of industries, around the world. Engineering, Design and Manufacturing are the fun and easy operations of our business. It’s getting to understand the Customer’s needs and more importantly, learning the level of their own understanding of what they are asking for that is the hard part of the business.

We see a trend here. Our customers are looking for a sight glass that fits their application. Typically, it’s an NPT sight glass, or an ASME sight window, or a totally non-standard geometry of mounting the housing into their higher-level assembly. Either way, the sight glass is using either a threaded housing, or flanged – bolt on housing. The sizes vary. The optical clarity, pressure & temperature ratings remain almost the same. It’s almost always a “sight glass with perfect optical clarity; holding 200+ bar of pressure, and operating at 350+ degrees Celsius”. A sight glass with these performance figures is considered a high pressure sight glass by some, or a high temperature sight glass by others, depending on who is asking for a quote. We would like to think of it as a crazy application sight glass where it has to be perfectly transparent, yet holds the pressure while the materials are about to melt. This is an exaggeration of the requirements; it’s just to make a point of the design challenges. And it would be a market winner to actually develop a product like this.

There is a lot of thought going into developing a product. Over time we’ve given a lot of that to such a product. Let’s see, we see a lot of requests, very similar requirements each time, it takes precious “time to market” to customize the design per the specification, it’s always more expensive than a similar stock product and it’s going to take 4- 6 weeks to make. What are the chances the customer will stay to see it through? Well, it’s 3 to 4 out of 10. So here is an insane thought, how about increase the odds by developing the “nearly crazy” product that almost always fits the custom spec? While at this, perhaps the number of requests will also increase and these requests turn into “buy it now” customers. Such a product being in stock, already developed in a number of sizes, say from 1/2″ to 2″ NPT sight glass, and 2″ to 6″ ASME flange options would help our would be customers speed up their projects. How many more developments would be moved along by this approach? Sight glass is a product used in making energy, discovery of new medicines, production of food, semiconductors. Who knows what else, but it is for certain that a sight glass is an important component in technological progress. It seems we owe it to our customers to develop a sight glass that can be a high pressure, high temperature performer. And if it’s not for technological progress, how else are we going to continue ourselves in the world of whatever problems we are trying to solve?

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Laser Window

Posted by on 12th May 2013

Lately we’ve been busy with building sapphire laser windows for the industry. Second to only diamonds in mechanical strength sapphire is the choice for not-so-easy-on-it applications. Sapphire laser windows are scratch resistant, have a wide transmission spectrum of light, (from 200nm to 6µm) and inert virtually to all chemicals, except molten salts (salts in liquid phase), and Hydrogen Fluoride above ambient temperature. A thin sapphire window can also hold a few thousand pounds per square inch of pressure.

With such credentials sapphire is the perfect window into aggressive process environments. The only disadvantage is its cost. We deal with cost by economies of scale, fabricating more windows and standardizing on sizes. This is a bit of a compromise between a totally custom design and a bit lower cost of a standard product that can be adapted into the customer’s higher level design. This is where some engineering between Encole and our customers can make sapphire laser windows possible in the final product. When it’s all said and done, our windows are installed in dairy and flour production plants, other food processing, plasma chambers, high pressure reactors, energy generation, oil & gas equipment and countless other applications.

Another factor reducing cost is how the window is mounted into the metal frame. We use high performance adhesives for low cost windows. When using O-rings, metal seals, and various gaskets, the cost goes up with increased complexity of the window assembly. Below is a picture of sapphire laser windows designed for food processing equipment. The window is only 1 mm thick. There are no mechanical seals, yet the assembly can hold some pressure and provides hermetically isolated space for the equipment laser sensors. The window is bonded to the frame using a special adhesive which needs to go through stages of mixing, application, post heating and baking. Where we saved money on simplicity of the assembly, we spent the time on fabrication. The time in this case was at a lower cost because of our almost automated assembly process.

Sapphire Window

Laser windows for food processing sensors.

One notable feature of this design, is how secure the window is mounted into the frame. It’s very secure, given it’s only 1mm thickness. We did not bond this window to its flat faces because with time the metal frame would expand and contract under changing temperature and would eventually break the bond between the sapphire and the metal. You see, sapphire expands and contracts at a different rate than the metal, when heated or cooled. So, we designed a way to mount the window accommodating the mismatch in thermal expansion. These windows have been working out there in the world somewhere for quite some time now. More are needed, shipping tomorrow.

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High Temperature Sight Glass

Posted by on 2nd May 2013

Operating temperatures of sight glasses often exceed 300C. This is the stated cutoff for fused sight glasses. Albeit, for smaller apertures, where thermal expansion of the metal housing is less of an issue, the glasses may operate at 300C+, however this is not a recommendation and needs to be tested before use.

Sight glasses that are specifically designed for temperatures up to 450C are of brazed type, where the glass is brazed to a metal housing. This is easier said than done as the glass is rarely brazed directly to a metal housing. First the glass is metallized, which is the process of depositing a thin layer of metal onto the edge of the glass. This is done by metal evaporation of metal splattering techniques. The metal being applied is typically Titanium. After the edge of the glass is coated with Titanium, then the brazing step follows. Brazing is typically done with clear materials such as sapphire or quartz, less often with borosilicate. This is because of differences in optical transmission and tolerance to thermal shock between these materials. Quartz has the best resistance to thermal shock among borosilicate, and sapphire. When brazing is done, the quartz (or sapphire) are brazed to a secondary sleeve, which later is then welded to the main housing. The purpose of this intermediate sleeve is to accommodate the inevitable mismatch in thermal expansion between metal and the quartz (or sapphire).

The sleeve usually has a thin wall thickness, in the order of 0.005 – to 0.030 inches, and it’s made of a type of Kovar that closer matches the coefficient of thermal expansion (CTE) of the sapphire or quartz. The entire assembly of the quartz, sleeve and the housing is designed in such a way as to remove any stresses from the sleeve. This is because the sleeve is thin. Here lies the challenge of this type of design: the sleeve by itself cannot take the working pressure of the product, yet, the sleeve creates a hermetic seal with the brazed quartz. The rest of the design is very particular about properly supporting the sleeve/quartz assembly. The axial stresses and the radial (hoop) stress of the assembly are transferred into the main housing. The result is the sight glass with fully supported quartz. Thinner sleeves are designed for Helium leak tight for vacuum applications, thicker sleeves for high pressures.

We took it upon ourselves to design a high temperature sight glass with no brazing. The advantages of that are potentially lower cost and better control of the assembly. This is a work in process and it involves metal seals made of Waspalloy.

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How to Get Rich and Help People

Posted by on 2nd April 2013

One of the primary metrics by which a charitable organization is judged is the percentage of the donations that are actually delivered to those in need. In other words: overhead. At first glance this seems reasonable. After all, you would like the money you donate to go to the starving children or abused puppies or disabled vets rather than see it “wasted” on office supplies or – worse – line the pockets of administrators.

However, we don’t take this attitude when buying goods or services. When shopping for cars no one asks how much of the purchase price actually goes to buying the component parts, and how much goes to the CEO. When acting as consumers we look at the cost we pay and the benefit we receive. If the benefit is worth the cost then we happily pay it without worrying about what happens to the money after it leaves our hands.

Why do we have such a different attitude when donating to charity? And should we? What is the benefit we receive in this case?

If the benefit is simply a tax write-off or a warm fuzzy feeling then perhaps our attitude towards giving makes sense. The more puppies get rescued, the fuzzier the feeling, so low overhead is key. And the fact that there are always more puppies to rescue means we can enjoy a tax benefit in perpetuity.

But if the goal of charity is to actually solve a problem then maybe overhead isn’t the right metric at all. So argues Dan Pallotta in a talk delivered at a recent TED conference in Long Beach, California. The talk is compelling and entertaining and definitely worth a look. It is essentially a condensation of Pallotta’s books Charity Case and Uncharitable.

One of his main points is that part of what counts as “overhead” is the cost of marketing and development. In other words: the cost of growth. And by forcing charities to keep their overhead low what we are doing is ensuring that they will always remain small. Too small to actually resolve the problems they seek to address. The proper metric, he argues, is not the fraction of the money raised that goes to the cause, but rather the total amount of money that is delivered.

Pallotta is in a unique position to know whereof he speaks, having founded a for-profit fund-raising organization called Pallotta TeamWorks (PTW). After raising hundreds of millions of dollars for charitable causes PTW was driven out of business by lawsuits and the resultant negative press.

And this is where things get tricky.

From the perspective of the plaintiffs in these cases Pallotta was a charlatan who over-promised and under-delivered. But from Pallotta’s perspective he was ridden out of town on a rail by the very narrow-minded, short-sighted Puritanical views of charity that he decries in his TED talk.

So who is right?

According to Pallotta, the donations to a fund-raising event for one breast cancer charity plummeted from $71M when he ran the event to $11M after they severed ties with PTW and ran the event themselves the following year. This seems to drive home the point that overhead is irrelevant if you are delivering more money.

But clearly there has to be a limit. If you raise $1B and deliver only $1M to charity that is an indication of a problem, even though $1M is a lot of money. So where is the line and how should we draw it?

In the private sector there is (at least in principle) a check on this sort of abuse due to competition. If a company funnels too much of its profits to top Management they will be at a competitive disadvantage against a company that re-invests its profits into business development activities. And in a way it is competition of this sort that is driving overheads down in charitable organizations. Charities are competing to have the lowest overhead as a way of demonstrating their virtuousness to potential donors.

If we want charities to actually be effective at eliminating problems like poverty and homelessness then what is required is a cultural shift in the attitudes of the giving public. Instead of asking charities about their overhead, we should be asking them: What is the scope of the problem you are trying to fix, what resources are required to address a problem of that scope, and what is your plan for raising the required resources?

And Pallotta – love him or hate him – has at least begun the conversation required to effect such a shift.

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Clear Sight Glass

Posted by on 30th October 2012

Clear Sight Glass

Optically clear sight glass compared to a non-lapped sight glass.

Looking inside a reactor chamber while the process is running can be a rich experience, literally. This type of experience goes on a resume of a progressive scientist and opens more career opportunities. This is one way of looking at the benefits of an optically clear sight glass. Another way to look at it is to recognize that the reactor under observation actually needs understanding of the process going on inside it. A better understanding of the process results in better control. Better control results in a better product, higher yields and lower production costs.

The benefits of a clear sight glass unarguably are very strong. In the picture we compare two sight glasses for optical clarity. Both sight glasses are NPT – threaded housing having glass fused to the metal. These are what is known as fused sight glasses, where the glass is melted inside the metal housing, then the glass cools down at the same time as the metal housing. The glass eventually solidifies, meaning it is no longer a liquid. The metal at that temperature is still hot as the glass continues to relax its stress post solidification. The glass is “annealing” at this temperature range. When the metal and the glass cool down to room temperature, the result is an inseparable assembly of glass and the metal. The product is mechanically very strong. The glass is literally fused to the metal and cannot be separated from it by force, only by chemically dissolving it. Mechanically, a fused sight glass is the safest type of sight glasses on the planet. They do not catastrophically break, they hold high pressures, can tolerate strong vibrational forces and large temperature swings. In every way, except one, fused sight glasses are superior to composite sight glasses, that is, assembled from discrete components.

The only potential disadvantage of a fused sight glass over a sight glass assembled from several components is the optical clarity. Potential that is, not actual. If a fused sight glass is lapped post fusing, this disadvantage goes away. By nature of melting the glass, simultaneous fusing it to metal and subsequent cooling, the glass becomes concave in the process. In other words, the glass surfaces are bowed, non-flat, lens-like, where the thickness of the glass in the center is thinner than at the walls. The glass during fusing “wets” the metal walls by capillary action and tends to creep up the wall surface. This is what makes fused glasses so strong in the first place and this “bowing” is inherent in all fused glasses if they are not post-lapped.

Post-lapped fused sight glasses are typically used in imaging systems requiring good optical clarity. Applications include in-tank camera systems, viewports for in- reactor cameras, as well as windows for a laser sensor.

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