over fire jets. WAS External reducing valves

NW Mailing List nw-mailing-list at nwhs.org
Wed Feb 13 16:45:21 EST 2019


I remember seeing the over fire jets and being told their function, but 
I did not know enough in those days to ask how they worked.

Gordon Hamilton

On 2/13/2019 4:14 PM, NW Mailing List wrote:
> Not I.
> EK
> *From:* NW Mailing List
> *Sent:* Wednesday, February 13, 2019 3:58 PM
> *To:* NW Mailing List
> *Subject:* Re: over fire jets. WAS External reducing valves
> I don’t know; maybe someone (like Ed King and Gordon Hamilton) on this 
> list has experience being around them.
> Bud Jeffries
> *From:* NW Mailing List
> *Sent:* Wednesday, February 13, 2019 2:13 PM
> *To:* NW Mailing List
> *Subject:* Re: over fire jets. WAS External reducing valves
> I believe the canisters on the outside are mufflers to reduce the 
> extremely loud sound of the air being pulled into the firebox.
>
> Jim Stapleton
> Northernmost VA
>
> On Feb 13, 2019, at 11:41, NW Mailing List <nw-mailing-list at nwhs.org> 
> wrote:
>
>> John, don’t know, but I doubt it.  What if a little dust was injected 
>> into the firebox, it was just sucked up the stack along with cinders 
>> and all.  Bud
>> *From:* NW Mailing List
>> *Sent:* Tuesday, February 12, 2019 8:25 PM
>> *To:* nw-mailing-list at nwhs.org
>> *Subject:* RE: External reducing valves
>>
>> Thanks Bud. Most helpful. Do you happen to know if the ‘cans’ hanging 
>> below each nozzle on the side of the firebox (S1a for example) were 
>> air intake filters?   John Garner
>>
>> *From:*NW Mailing List [mailto:nw-mailing-list at nwhs.org]
>> *Sent:* Tuesday, February 12, 2019 6:51 PM
>> *To:* NW Mailing List <nw-mailing-list at nwhs.org>
>> *Subject:* Re: External reducing valves
>>
>> John,
>>
>> The jets were controlled from the cab. The position of the jets were 
>> along the firebox side and were staggered so that a jet on one side 
>> was not exactly opposite the other side.  I don’t know about being 
>> adjustable, but they did use a steam nozzle that drew air in through 
>> an orifice using the venturi (spelling?) effect.  N&W only used 
>> overfire air jets on yard engines and if the exhaust and draft was 
>> heavy the jets would be off, and if the engine was halted or working 
>> with the light exhaust and draft, the engineer could turn the jets to 
>> get more complete combustion.
>>
>> Hope this helps,
>>
>> Bud Jeffries
>>
>> *From:*NW Mailing List
>>
>> *Sent:*Tuesday, February 12, 2019 12:19 PM
>>
>> *To:*nw-mailing-list at nwhs.org
>>
>> *Subject:*RE: External reducing valves
>>
>> Bud,  Can you briefly explain the operation of these jets? Were they 
>> automatic or controlled by crew? Was air flow adjustable or just 
>> on/off? Was steam used as the power source to achieve the necessary 
>> air flow? Thanks,   John Garner
>>
>> *From:*NW Mailing List [mailto:nw-mailing-list at nwhs.org]
>> *Sent:* Tuesday, February 12, 2019 10:29 AM
>> *To:* NW Mailing List <nw-mailing-list at nwhs.org>
>> *Subject:* Re: External reducing valves
>>
>> N&W tested the use of overfire air jets for road service in 1944 with 
>> 2151.  With heavy exhaust creating very good draft in road service, 
>> the railway found that the jets gave no appreciable benefit.  
>> Overfire air jets did find favor for use on locomotives in yard 
>> service where draft was much more sporadic and often not heavy.
>>
>> Bud Jeffries
>>
>> *From:*NW Mailing List
>>
>> *Sent:*Monday, February 11, 2019 4:54 PM
>>
>> *To:*NW Mailing List
>>
>> *Subject:*Re: External reducing valves
>>
>> Speed didn’t have anything to do with the use of overfire air jets.  
>> Rio Grande had some big Baldwin 4-6-6-4s with overfire jets.
>>
>> Their function was to kill smoke by introducing air over the fire to 
>> more thoroughly burn the fuel. The first tests of them on the N&W 
>> were on a Z-1a (1352) and a W-2 0-8-0 (if I recall correctly the 
>> 680).  The tests were done at Bluefield Yard; the catenary was in 
>> full view. There are at least two N&W photographs of the test.  I 
>> don’t know the date, but it was before the electrification was done 
>> away with.
>>
>> Ed King
>>
>> *From:*NW Mailing List via NW-Mailing-List
>>
>> *Sent:*Monday, February 11, 2019 3:02 PM
>>
>> *To:*NW Mailing List
>>
>> *Cc:*NW Mailing List
>>
>> *Subject:*Re: External reducing valves
>>
>> While on N&W steam : Most all the 0-8-0 switchers had over the fire 
>> air jets-- I'm guessing to aid in keeping a hot fire because of their 
>> slow mundane work vs the faster road locos had speed to help in 
>> firing. Is that the only reason for the jets ?  Ron Hash
>>
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