by Thermo 19. September 2013 17:04

Methanol Matters

Dear Famous Frog,

Methanol is both poisonous and explosive. What precautions will be taken by the circuit owner or Novinium if the cable, cable components, or injection equipment were to leak Ultrinium™ 732 fluid and mix with water (i.e. flooded vault scenario)?

West Coaster

 

Dear Coaster-

First let’s chat about the word “explosive.” Flour is explosive if you mix a bunch of flour with air in just the right concentration. I suspect you have flour in your house, but I doubt you keep it in an explosion-proof cabinet. Analogous to the flour in your home, the methanol that is liberated by the reaction of methoxysilanes (The predominant class of materials employed to rejuvenate URD cables and including Ultrinium 732 fluid) has an extremely low explosion risk. I’ll explain why that is so later.

Next, let’s talk about the word “poisonous.” Methanol can be found in your garage. Methanol is typically 30% to 50% of the blue windshield washer fluid used in your automobile. There are two primary precautions to avoid methanol poisoning. The first precaution is to not drink the water in your flooded vault scenario. That’s good advice for a host of reasons. The second precaution is to avoid breathing methanol vapors. This is easily achieved by ventilation of vaults before humans enter. When present, methanol vapors register with the devices commonly utilized to test the safety of air before people enter a confined space. In unconfined spaces, natural ventilation will keep the methanol concentration very low. There is methanol in wine and apple juice, so small quantities are not at issue. If somebody smells a strong solvent-like smell the space should be exited. To reduce the methanol concentration increase the ventilation, remove the spill with a vacuum truck or other means, and/or dilute with more water.

There are four reasons why methanol is not a particularity great explosion or poison risk with Novinium® brand rejuvenation:

1. Novinium’s preferred injection method, sustained pressure rejuvenation or SPR does not involve unattended feed tanks. In the unlikely event that a leak does occur it can be stopped quickly, limiting the magnitude of the spill. SPR is a patented process available only from Novinium. The patented injection adapters (IAs) used at the cable ends are extraordinarily robust and unlikely to leak. The cable itself cannot leak unless it fails dielectrically. Failure with SPR occurs in fewer than 0.2% of treated cables. In the event of a dielectric failure only a small amount of fluid is likely to leak. The amount of fluid that can leak depends on the size of the cable and how long prior to the failure the cable was rejuvenated. Rules of thumb to estimate leak size are available in Novinium Rejuvenation Instruction 99, Cutting a Treated Cable (NRI99). For a typical URD cable the spill size is most likely less than a cup of coffee.

2. When the second-best approach is utilized, improved unsustained pressure rejuvenation or iUPR a feed tank is typically left attached to the cable for about 24 hours. There is no soak period. A soak period involves the use of soak tank reservoirs for multi-month periods. The exposure to a potential leak with iUPR is typically 60-times less than the 25-year old unimproved-UPR technology. “iUPR” is made possible by Novinium patented technology.

3. Methoxysilanes react slowly with water to liberate methanol. The speed of this reaction is limited by two main factors. First, alkoxysilanes are not appreciably water soluble so a spill into water creates two liquid phases – like vinegar and oil. The reaction occurs primarily at the phase interface – this slows the evolution of methanol. Second the reaction is naturally slow – full reaction would occur over the course of hours. The volume of methoxysilane, such as Ultrinium 732 fluid, used to treat cables is very small. For example, 19 strand cables require less than a gallon to treat 1000 feet. In your “flooded vault scenario” there will likely be many, many gallons of water and any methanol formed is quickly diluted in the water. The volume of patented Ultrinium fluids required to treat cables is typically about 30% less than the volume required by older approaches.

4. Methanol is very soluble in water – in fact water and methanol are infinitely miscible. When methanol is mixed with water its vapor pressure is greatly reduced as is its toxicity. In other words, water mitigates methanol issues with all Novinium technologies. The more water the better. Unfortunately the flammability and explosion risks associated with CableCURE®/XL fluid are not mitigated by water, because that material includes a highly flammable material, trimethylmethoxysilane (TMMS), that is not water soluble. For a thorough discussion see Flash Point Matters.

Safer is better,

TBF

 

CableCURE is a registered trademark of UTILX Corp.

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Safety Matters

by Thermo 18. October 2012 20:04

Flash Point Matters

Dear Fabulous Frog,

Why is the flash point of a rejuvenation fluid even relevant? The temperature of an electrical arc is 35,000°F – everything is flammable from the utility standpoint, just as we know that nothing is unbreakable from a lineman’s viewpoint.

West Coast New Yorker

Standards Engineering


Editors Note: It has been my practice to keep my posts to no more than a single page. I had to depart from that practice on this post, because the topic was too hot and too integrated to split into several smaller posts. The time spent on this prose will be worthwhile.

-T. B. Frog

Dear Ms. Yorker-

That’s a really interesting question and a great learning opportunity. I touched upon this subject in two previous posts in 2010 and 2011, but 2012 is a new year so let’s take a fresh and more comprehensive look.


Post Date

Post Title & Link

2011-11-02

Fluid Flammability

2010-05-14

Flash Point & Flammability

Before we dive out of the frying pan and into the fire, I want to comment on the quip, “… unbreakable from a lineman’s viewpoint.” Linemen take great pride on being able to break anything, and as we shall see later, the fallibility of equipment, the inevitability of equipment failure (whether or not that failure is encouraged by rough handling of burley line-personnel), the certainty that fluid will one day be released into the confined volume of your pad-mounted transformer, are precisely why this issue is so important.

Let’s reproduce a table of closed cup flash points from the November 2, 2011 post, because the values are very important. The materials with a red background are defined as flammable liquids by OSHA 29 CFR 1910.1200(c) and DOT 49 CFR 173.115-120.

Material

Flash Point

CableCURE®/SD fluid

     32°F   (0°C)

CableCURE®/XL fluid

     55°F  (13°C)

Jet Fuel A

   100°F  (38°C)

Perficio™ 011 fluid

   142°F  (61°C)

Ultrinium™ 732 fluids

 >142°F  (61°C)

CableCURE®/DMDB fluid

   174°F  (79°C)

Ultrinium™ 733 fluids

 >248°F (120°C)

It’s also important to understand what a closed cup flash point represents. Referring to ASTM D93-10 (Standard Test Method for Flash Point by Pensky-Martens Closed Cup Tester), a sample of fluid is placed in a closed metal cup at a temperature well below its flash point. The fluid and the air/vapor space above the fluid are well mixed as the temperature of the cup and its contents are uniformly increased at a prescribed rate of 5 to 6°C (9 to 11°F) per minute. A small shutter is opened at each 1°C increment, and an ignition source is lowered quickly (0.5 seconds) into the vapor space of the test cup. The ignition source lingers in its lowered position for 1 second. It is then quickly raised and the shutter is closed. This process is repeated until the vapor-air mixture flashes. The ignition source might be a propane flame or a spark. The temperature of the ignition source has zero impact on the flash point. That’s right, it does not matter what the temperature of an arc is – it may be 35,000°F or 35 million. It’s the temperature of the fluid that determines whether an ignition occurs.

Here’s why that is the case. I think everybody is familiar with the “fire triangle,” I illustrate nearby. In order for a fire or explosion to occur, there must be three things: A source of ignition, fuel, and oxygen. Part of Ms. Yorker’s point is that in medium and high voltage environments, sources of ignition are common. Of course, oxygen is also ubiquitous and hence the only thing that is missing to create a fire or explosion is the fuel. But just having fuel is still not enough! As we discussed previously, a spill of fluid (fuel) is inevitable, despite Herculean engineering and procedural efforts to prevent that event. For now, let’s assume the spill does occur from a tank failure, a failure of one of the fittings, the tubing, or an injection elbow. What happens next?  Check out Frogograph 1 nearby. The fluid will flow to the lowest point of the transformer enclosure. There may be a puddle or perhaps just fluid-wetted soil.  In Frogograph 1, the temperature at the bottom of the transformer is lower than the flash point. The flash point is indicated by the red “FP” arrow. Because the temperature is well below the flash point, there will not be enough fluid evaporation to reach the lower explosive limit (LEL). I’m perfectly safe standing there drinking my coffee.

The situation changes in Frogograph 2 as the temperature just exceeds the flash point. Now in addition to the blue liquid layer, there are three other possible strata, labeled <LEL, Goldilocks, and >UEL. Let’s start from the bottom – the UEL is the upper explosive limit. All flammable fluids require a threshold amount of oxygen to burn. As a practical matter, this light green stratum is very, very shallow and since the likely sources of ignition are higher within the enclosure, its presence is largely irrelevant. Now let’s jump to the uppermost stratum left clear in the illustrations.  In this stratum there may be some molecules of evaporated fluid, but there simply is not enough to ignite in a self-propagating chain reaction. It’s the red stratum, the “Goldilocks” zone, where there is just enough (not too much and not too little) fuel (vaporized fluid) and just enough (not too much and not too little) oxygen to support combustion. Because the transformer enclosure is not well ventilated and because the flammable vapors are heavier than air, these strata form at the bottom as illustrated. When a fluid vaporizes, its volume increases about 1000-fold, so even a small spill has the potential to create a large Goldilocks stratum. The rate of fluid evaporation is related to the difference between the temperature at the bottom of the enclosure and the flash point. The higher the flash point, the lower the rate of evaporation will be. There are three things that mitigate an increase in depth of the Goldilocks zone. Gravity will draw the spilled fluid into the soil. Secondly, enclosures are not air-tight and hence restrained convection will remove some of the vapor. Thirdly, my favorite law of thermodynamics, the 2nd law or entropy, helps disperse the spill. Both liquid and vapor diffuse through air and soil acting to reduce the concentration of the fluid vapors. The Goldilocks stratum is checked by these three phenomena. For a given spill, the depth of the Goldilocks stratum will be determined by the difference between the temperature at the bottom of the enclosure and the flash point.

In Frogograph 3 the temperature is well above the flash point and the Goldilocks stratum is much larger. In this illustration, we imagine that the neutral bleed wire to the elbow does not make an adequate electrical connection and discharges occur at that point. As the Goldilocks stratum enlarges it eventually reaches this discharge and the Goldilocks volume ignites. Because the transformer provides mechanical confinement an explosion occurs and the lid is blown open violently.  That is precisely what happened in the photograph nearby to an Ohio circuit owner. Fortunately, no tadpoles were playing nearby.

Now go back to the flash point table above. Does the temperature in your transformer enclosures ever exceed 55°F (13°C)? Unless you are on the North Slope of Alaska, the answer is probably yes. If Alaska Airlines asks if they can store one gallon of jet fuel A in each of your enclosures, would you say yes? The jet fuel would be safer than the low flash point injection fluids.

How many fires and explosions would be too many on your system? Some may be stammering, “But, … but, we have never had a fire or explosion with the flammable rejuvenation fluid we have used in the past.” Lucky you … others have! As a standards engineer you should demand that all suppliers provide a complete accounting of all fires and explosions its process and fluid have ever experienced. If a vendor is unwilling to comply with this most reasonable request, you can disqualify that supplier. Let me preemptively supply the Novinium list … boring as it may be.

Novinium fires and explosions   (as of October 18, 2012)

Event Date

Event Description

 

 

 

 

 

 

A partial compilation of fires and explosions suffered by circuit owners utilizing flammable rejuvenation fluid can be found at …

http://www.novinium.com/pdf/papers/Rejuvenation_Hazards_Analysis.pdf

... in Addendum C of the Rejuvenation Hazards Analysis, beginning at section 2.3.3. Specific examples are illustrated at 2.3.3.1.3b, 2.3.3.1.3.1.2c, 2.3.3.2.1c, and 2.3.3.2.2c. There are many more.

Thankfully, most of us have never been in a head-on auto accident, but we take comfort in the PPE designed into our cars, namely the seat belts and air-bags. We pay more for these features on our cars, not because we have had a serious accident, but because we wish to avoid the terrible consequences of such an event should it occur. Even better than seat belts and air bags, imagine a system that eliminated the risk of collision altogether.

Such a system is available to circuit owners enjoying the capital efficiency of rejuvenation. My final illustration in this post is the “Hierarchy of Control” nearby. The upside-down pyramid illustrates that the most effective way to deal with safety risks is to eliminate them. At Novinium we embrace this hierarchy and you should too. Eliminate known risks, substitute safer materials and processes for those that are less safe. Apply concentrated engineering effort to prevent occurrences and mitigate the impact when unfortunate and inevitable incidents do occur. Implement, but depend the least on administrative, behavior-based, and PPE controls.

With flash points greater than 142°F for Novinium’s Perfico™ 011 fluid and Ultrinium ™ 732 fluids (both of which enjoy patented methods including U.S. patents 7,658,808, 7,700,871 and 8,101,034 together with their foreign equivalents), fires are extraordinarily unlikely. But we don’t stop there. With our improved unsustained pressure rejuvenation (iUPR) we eliminate the 60 to 90 day soak period employed by the two-decade-old approach altogether. That’s about a 60-fold reduction in the exposure to a leak in the first place. With our patented sustained pressure rejuvenation (SPR) process (U.S. patents 7,615,247 and 8,205,326 and foreign equivalents) and associated injection adaptors (U.S. patents 7,195,504, 7,538,274 and 7,683,260 and foreign equivalents), the possibility of a leak is entirely eliminated. There’s more – a lot more. To understand how technology has vastly improved the safety performance of rejuvenation technology, see …

A Comparison of Rejuvenation Hazards
January 19,2011

  • Hazard-by-hazard analysis of commercially significant rejuvenation technologies used for URD cables
  • Differences between sustained pressure rejuvenation (SRP) and unsustained pressure rejuvenation (UPR)
  • Differences between CableCURE™ fluid, Perficio™ fluid, and Ultrinium™ fluids
  • Rejuvenation risk mitigation strategies 

So here is the bottom line in my longest ever post.  Flash points and the impact they have on safety are in the public domain.  What will you say on the witness stand in defense of your firm when somebody or some frog is hurt by using the least safe technology?  To help you on the stand, cut out the handy cheat-sheet below and check all that apply.

 

We only care about the lowest price.

 

We thought flash point was the point at which a photographer had to use a flash.

We never looked at the MSDS.

We had done it this way for over a decade and we never had this problem before.

The supplier assured us that there was nothing to worry about.

I always use the oldest technology. I would still be using a rotary phone if I could find one.

Better safe than sorry,

Thermonuclear Bull Frog

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Safety Matters

by Thermo 2. November 2011 21:46
Fluid Flammability
Dear Wet One,
Our construction centers have posed the following questions:
1.      Is the injection fluid flammable after the cable has been treated?  If yes, for how long?
2.      Is it safe for our crews to splice a failed cable that has been injected?  What type of precautions do they need to take when working with cable filled with injection fluid?
Can you provide some froguidance?
Seeking Answers in San Antonio
Dear SASA-
Before I can answer the first question it is useful to define the word, flammable.  In a practical sense flammability is meant to convey the ease with which a material may be ignited.  Highly flammable materials are easy to ignite; non-flammable materials are more difficult to ignite.  Flash Points are an objective measure of flammability.  The lower the flash point the more flammable the material.  In the United States two arms of the U.S. government provide definitions for what is flammable, what is combustible, or not combustible. You have to love the government; its two agencies promulgate inconsistent definitions.  This means that when one uses the words “flammable,” “combustible,” “not flammable,” and “not combustible,” one needs to define whether they are using the Occupational Health and Safety Administration (OHSA) definitions or the definitions of the Department of Transportation (DOT) .  Definitions in other countries may or may not be the same as those provided by Uncle Sam.  The table nearby provides those definitions and the regulatory citations.  As a practical thinker I prefer to avoid the regulatory morass and simply compare flash points. The higher the flash point the less likely the fluid will ignite in a specific field circumstance.
A liquid’s flash point is an indication of the temperature at which sufficient flammable vapors have evaporated to allow for ignition and the propagation of flame when exposed to an ignition source (spark/flame).  The higher the flash point the less likely a fluid will ignite in otherwise identical circumstances.

In the second table nearby the flash points of some common substances are listed along with commercially utilized cable rejuvenation fluids ordered from most flammable to least flammable.  The first four items in the table meet the DOT and OSHA definition of flammable.  At Novinium we have an unwavering commitment to safety so we are loath to use flammable materials.  The simple answer to your first question is – no!

Using non-flammable fluid is not the only way Novinium reduces exposure to fire and explosion hazards.  A second very important way is to limit the period of time that injection bottles are connected to energized cables.  The probability that a leak will occur is related to the length of time that a feed or a soak bottle is connected to a cable.  Whether utilizing Novinium’s patented sustained pressure rejuvenation (SPR) or the older but improved unsustained pressure rejuvenation (iUPR), Novinium’s patented catalyst technology eliminates the need for a soak period completely.  Approaches that don’t utilize Novinium’s patented catalyst technology require soak periods of 60 days or more for most 7-strand and 19-strand conductors.  Utilizing Novinium technology typically reduces the exposure to leaking fluids over 60-fold. For a thorough description of all of the rejuvenation dimensions of safety including even more about flash points and flammability my colleagues, Rich and Glen provide an 89-page treatise, “A Comparison of Rejuvenation Hazards & Compatibility.”

With regard to your second question, there are indeed sensible precautions that your crews should take when working with cable filled with injection fluid.  Novinium has a six-page illustrated instruction sheet, “Rejuvenation Instructions:  Cutting a Novinium™ treated cable” which provides the required background and instructions.  Click here to download a copy.  Do not use these instructions for fluids not supplied by Novinium as additional safety precautions would be prudent for those more flammable materials.
My advice to you is to never compromise safety.  State-of-the-art patented technology and non-flammable fluids for URD cables are available only from Novinium.  For high temperature feeder cable applications Novinium has the only fluid with a flash point higher than the maximum operating temperature of the cable.
Practice safe rejuvenation,
Thermo

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Safety Matters

by Thermo 14. May 2010 20:32

Flash Point & Flammability

Dear Wet One,

What is a flash point and how important is the flash point in rejuvenation safety?

Charred in Columbus

Dear Charred-

I like to keep warm more than the average girl, but there is warm and then there is warm.  To keep cool I keep my skin moist and I avoid situations where I could possibly be exposed to fires.  Before I answer your query, let's review some principles.  There are three things required for a fire or explosion,

  1. oxygen (generally in the guise of air)
  2. a source of ignition, which is often readily available in electrical distribution and transmission environments, and
  3. fuel. More...

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Safety Matters

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