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Architecture & Construction - Distilled Spirits Plants

alcohol

What is the LFL & What does it mean to you?

What is the LFL?

The LFL (Lower Flammable Limit) is a concept related to flammability & fire safety. 

The LFL is defined as :

Usually expressed in volume per cent, is the lower end of the concentration range over which a flammable mixture of gas or vapour in air can be ignited at a given temperature and pressure. The flammability range is delineated by the upper and lower flammability limits. Outside this range of air/vapor mixtures, the mixture can not be ignited…

https://en.wikipedia.org/wiki/Lower_flammable_limit

For ethanol, aka alcohol, the LFL is 3.3% by volume. Meaning, if ratio of ethanol vapor to air is less than 3.3%, the vapor can not ignite. 

This diagram below demonstrates the limits of the LFL of ethanol, as well as the UFL (Upper Flammable Limit). 

Why Does This Matter?

Knowing what the LFL is, and ensuring that flammable vapors, such as ethanol vapors, remain under this limit is a commonly used, well established, and reliable method of ensuring a safe, fire free environment. 

In order to have an alcohol fire, you need:

  1. The Fuel (Alcohol)
  2. Oxygen
  3. Ignition Source (Spark, Heat)

Take away one of these elements, and you can avoid a fire! In this case, we commonly remove the fuel, at least most of the fuel to stay under the LFL!

How do we stay under the LFL?

I’ll get right to it…VENTILATION.
This is the key in keeping under the LFL and keeping safe. If you exhaust out more ethanol vapors than can ever be accumulated and you’ve ensured that the flammable range can never be reached. For most requirements in the codes using the LFL to avoid fires, it usually requires 25% of the (3.3%) LFL. So, for ethanol that would be .825% ethanol vapor in the air. This is essentially a factor of safety.

As shown in the photo below, exhaust is usually achieved via duct, brought to 12″ above the floor, because ethanol vapor is heavier than air, and will settle near the floor. These exhaust ducts may be near any potential ethanol vapor leak, such as near a still (for a possible breach), near tanks, and near barrels. Exhaust is normally powered by an exhaust fan on the roof, and there must be an intake make up air vent to replace the exhausted air. 

 

 

Keeping under the LFL is a very important safety feature in a distillery. It takes a preventative approach of avoiding  a fire in the first place, rather than mitigating a fire after it has occurred. 

Written By:

Matthew Taylor-Rennert

Prohibition On Flammable Liquids In Plastic Totes

What Are IBC Plastic Totes and what is prohibited from being stored in them?

If you’ve been to a few distilleries, you might have seen these around: Large plastic IBC (intermediate bulk container) totes.

IBC totes are lightweight, come in a variety of sizes (often seen in 275 gallons or more),  and are affordable. They are great for storing water and some other nonhazardous liquids, but they are actually prohibited by code to be used to store certain flammable liquids inside buildings, including alcohol over about 16% ABV.

Where in the code is this prohibited?

The building and fire codes can be tricky. Below is the code path that leads to this determination:

2012 IFC Chapter 2
Definitions- Tank, Portable
A packaging of more than 60-gallon capacity and designed primarily to be loaded into or on or temporarily attached to a transport vehicle or shop and equipped with skids, mountings or accessories to facilitate handling of tank by mechanical means. It does not include any cylinder having less than a 1,000-pound water capacity, cargo tank, tank car tank or trailers carrying cylinders of more than 1,000-pound water capacity.

2012 IFC 5704.3
Container & Portable Tank Storage
Storage of flammable & combustible liquids in closed containers that do not exceed 60 gallons in individual capacity & portable tanks that do not exceed 660 gallons in individual capacity, and limited transfers incidental thereto, shall comply with sections 5704.3.1 through 5704.3.8.5.

2012 IFC 5704.3.1
Design, construction & capacity of containers & portable tanks
The design, construction, & capacity of containers for the storage of Class I, II, & IIIA liquids shall be in accordance with this section & section 9.4 of NFPA30.

2015 NFPA30 9.4.3
The maximum allowable size of container, intermediate bulk container, or metal portable tank for class I, II, & IIIA liquids shall not exceed that specified in table 9.4.3

2015 NFPA 30 Table 9.4.3
Chart shows that  IBCs & Composite IBCs are NP (Not Permitted) in Any Size to have Class IB & IC Flammable liquids stored in them. Chart also shows that Approved metal portable tanks and IBCS are permitted up to 793 gallons in size, containing Class IB & IC Flammable liquids.

Why are spirits delivered in plastic totes, and why is it dangerous?

Grain Neutral Spirits are often delivered in plastic totes. The main reason for this is that when they are in transit, they are subject to the department of transportation regulations. Once they enter a building, they are subject to the local jurisdiction’s adoptions of the code, usually some version of the International Building/ Fire codes & NFPA standards mentioned above.

The primary reason for these code prohibitions are that plastic is combustible, and can build up a static charge with no way of being dissipated. This could potentially create a spark that could potentially quickly spread to the plastic.

What other options are there?

The answer is simple: metal! Essentially metal containers are permitted to be used to store large quantities of spirits. Of course, there are many other regulations regarding these containers including but not limited to: static grounding, fire protection, secondary containment, spacing, etc.

When selecting a portable container to store spirits at your distillery, metal is the safe and smart way to go!

 

Article by:

Matthew Taylor-Rennert

Dalkita Architecture & Construction