Bilge Blowers - Dangerous?

[45Auto]

Re: Bilge Blowers - Dangerous?

Definition of marine ignition protection:

TITLE 33 - NAVIGATION AND NAVIGABLE WATERS​

CHAPTER I - COAST GUARD, DEPARTMENT OF HOMELAND SECURITY​

SUBCHAPTER S - BOATING SAFETY​

PART 183 - BOATS AND ASSOCIATED EQUIPMENT​

subpart i - ELECTRICAL SYSTEMS​

183.410 - Ignition protection.​

(a) Each electrical component must not ignite a propane gas and air mixture that is 4.25 to 5.25 percent propane gas by volume surrounding the electrical component when it is operated at each of its manufacturer rated voltages and current loadings, unless it is isolated from gasoline fuel sources, such as engines, and valves, connections, or other fittings in vent lines, fill lines, distribution lines or on fuel tanks, in accordance with paragraph (b) of this section.​

(b) An electrical component is isolated from a gasoline fuel source if: (1) A bulkhead that meets the requirements of paragraph (c) of this section is between the electrical component and the gasoline fuel source; (2) The electrical component is: (i) Lower than the gasoline fuel source and a means is provided to prevent fuel and fuel vapors that may leak from the gasoline fuel source from becoming exposed to the electrical component; or (ii) Higher than the gasoline fuel source and a deck or other enclosure is between it and the gasoline fuel source; or (3) The space between the electrical component and the gasoline fuel source is at least two feet and the space is open to the atmosphere.​

(c) Each bulkhead required by paragraph (b)(1) of this section must: (1) Separate the electrical component from the gasoline fuel source and extend both vertically and horizontally the distance of the open space between the fuel source and the ignition source; (2) Resist a water level that is 12 inches high or one-third of the maximum height of the bulkhead, whichever is less, without seepage of more than one-quarter fluid ounce of fresh water per hour; and (3) Have no opening located higher than 12 inches or one-third the maximum height of the bulkhead, whichever is less, unless the opening is used for the passage of conductors, piping, ventilation ducts, mechanical equipment, and similar items, or doors, hatches, and access panels, and the maximum annular space around each item or door, hatch or access panel must not be more than one-quarter inch.​

 

[JoLin]

Re: Bilge Blowers - Dangerous?

I hit the blowers as soon as I step on the boat. Then I open the hatches to check the fluids on both motors prior to start up. Should I be opening the hatches before hitting the blowers, to check for fumes? I always assumed they were ignition protected, given what they are required for.

Yes, you should open the motor hatch and get your nose down there before you switch on anything. Then run the blower for 3-5 minutes before starting the motor.

When fueling, ALL hatches and ports should be CLOSED. After fueling, open the motor hatch and sniff, then turn on blower for 3-5 minutes before starting the motor.

Those are the procedures proscribed by USCG and ABYC. I follow them.

My .02

 

[generator12]

Re: Bilge Blowers - Dangerous?

Totally an unfair comparison!

I have worked as a designer in the petroleum industry, design equipment for use in hazardous locations. I am familiar with the regulations as well as the science and engineering behind them.

Having recently returned to boating and having replaced a couple of blowers, I was struck by the cheap style of motors used. I would not have considered them explosion proof - they certainly would not pass any CSA or UL test for hazardous locations! I would have expected a sealed case rather than an open frame.

However, the saving grace MAY BE in the voltage/current required to achieve ignition of an explosive vapour and the low current at which these motors run. The current may be limited enough that ignition can't be achieved. The problem is that to meet UL criteria, ignition can not be achieved even with one fault introduced and I KNOW these motors would fail on that basis.

I have seen LOTS of products marked claiming to "meet code" when in fact they have never been formally tested and none have blown up yet! I have even seen products marked "UL Approved" that do not meet code!

You are justified in being skeptical

EXACTLY why I brought up the subject in the forum.

Someone commented earlier that if this were a dangerous situation it would have proven out in practice - boats would be exploding because of it. And he's right; they're not and therefore it appears that these devices are performing acceptably in this context.

Yet, I can't be confident that - CG approved or not - the thin plastic body on my bilge blower will prevent ignition of the surrounding atmosphere if vapors manage to enter it.

As an electrician in a prior incarnation (MANY years ago) I had to seal any installed junction boxes against such ignition; ensure that each lighting fixture , switch enclosure, motor, etc. incorporated such protection.

I guess the answer is, as also stated above, to vent the engine enclosure manually (i.e., open it up for a few minutes) before operating, and use the blower to sustain a safe atmosphere once it has been achieved.

 

[DianneB]

Re: Bilge Blowers - Dangerous?

... if this were a dangerous situation it would have proven out in practice - boats would be exploding because of it.

My thoughts exactly and that's why I use mine ..... But I wish I still had access to a test lab LOL!

 

[25thmustang]

Re: Bilge Blowers - Dangerous?

Yes, you should open the motor hatch and get your nose down there before you switch on anything. Then run the blower for 3-5 minutes before starting the motor.

When fueling, ALL hatches and ports should be CLOSED. After fueling, open the motor hatch and sniff, then turn on blower for 3-5 minutes before starting the motor.

Those are the procedures proscribed by USCG and ABYC. I follow them.

My .02

Looks like I should reverse my steps. The hatches are always opened, I just always hit the blowers prior. Won't take much for me to open the hatches first, then hit the blower.

When I fueled the boat, it was my first time with this one. I opened the hatches shortly after I started to fuel, to see if there was any leaking, or stray fumes. I had them open for a bit while poking around, but it sounds as though thats a bad idea. My question is this... what if there was a leak in the fill hose? Should I have pumped the fuel until a problem arose, before opening the hatch and seeing the issue? I had them open to see if there was anything bad happening (due to the boat being new to me).

Just something I would like to note for the future.

 

[shrew]

Re: Bilge Blowers - Dangerous?

Here is one last thought on this subject. Blowers are intended to vent explosive vapors to prevent fire and explosions. It would be a paradox to have the device intended to vent fule vapors ingnite the vapors that it was intended to vent. If there were no fule vapors there would be no need for a blower. If the blower inadvertantly ignited the fuel vapor, it wouldn't really solve anything, but rather be a one time use item which also blows up the boat up in the process. Not very effective.

 

[nofuss]

Re: Bilge Blowers - Dangerous?

Looks like I should reverse my steps. The hatches are always opened, I just always hit the blowers prior. Won't take much for me to open the hatches first, then hit the blower.

When I fueled the boat, it was my first time with this one. I opened the hatches shortly after I started to fuel, to see if there was any leaking, or stray fumes. I had them open for a bit while poking around, but it sounds as though thats a bad idea. My question is this... what if there was a leak in the fill hose? Should I have pumped the fuel until a problem arose, before opening the hatch and seeing the issue? I had them open to see if there was anything bad happening (due to the boat being new to me).

Just something I would like to note for the future.

When fueling it is recomended to leave the hatch closed as this would allow the fume build up, to be easier recognised by the sniff test or fume detector, when they are opened after fueling.
However on a NEW of new to you boat it would be prudent to have the hatches open and check the fill vent and supply lines. you never know there may not be a slight leak as is checked for by the closed hatch test, but instead an open line.
when i bought my second boat it had a fill cap on the deck which had a hose on to it that was open on the other end. and another one below the bow which was used to fill the tank. if the gas pump guy did not know the boat i would have fueled my bilge and spoiled a great day out.

 

[metalwizard]

Re: Bilge Blowers - Dangerous?

My boat is Little (18 foot) I/O the gap between the back of the "HOOD" and the back of the motor is about a foot wide. also there are 4 vents two facing forward two facing back. towing the boat to the dock should vent the compartment clear. I don't think I would EVER worry about fumes igniting.

Also the vents are supposed to vent fumes by the gas tank. my tank is under the glove box. nowhere near the engine. so blowers in the engine compartment would do NOTHING for venting those kind of fumes.

Basically the blowers on my boat are ornaments. I don't think they would do anything EXTRA for me. BUT

I am sure there are boats that sit at the dock for days at a time, and the engine compartments are sealed. or atleast sealed enough to hold some fumes.
Running a blower should be done. ANY company building a boat should be smart enough to use SEALED motors in a Hazardous location. turning your blowers on it just smart. and it's really cheap insurance.

 

[jeeperman]

Re: Bilge Blowers - Dangerous?

Here is one last thought on this subject. Blowers are intended to vent explosive vapors to prevent fire and explosions. It would be a paradox to have the device intended to vent fule vapors ingnite the vapors that it was intended to vent. If there were no fule vapors there would be no need for a blower. If the blower inadvertantly ignited the fuel vapor, it wouldn't really solve anything, but rather be a one time use item which also blows up the boat up in the process. Not very effective.

I agree with generator12, the regs seem to be bass ackwards.
Blowers should be purging explosive vapors, not venting (sucking) them out.

In order to purge or vent a confined space, you need a fresh air source via other vents or openings.

So to me a blower should be blowing fresh air source into the confined space and out the static vents. Then there is no need for explosion proof motors, etc.