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Onan Generators Restoring, operating and maintaining vintage Onan generators.

Onan Generators

Newbie with 30.0 EK-15R/1933D


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  #1  
Old 11-08-2017, 09:44:35 AM
ChapinGuy ChapinGuy is offline
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Default Newbie with 30.0 EK-15R/1933D

Hello all ... I'm a newbie and just purchased this unit. I know it is currently setup for NG at 208V-3P and runs perfectly as such. It was highly maintained by the company I work for since new. It has very low loaded hours. It is in excellent condition with only typical oil leaks at the front main seal and valve cover gasket It is a little dirty now but was very clean prior to recent construction in the area. The serial number is 0571300010.
I want to convert to LPG and 120/240-1P. As I learn from info found here:
The unit is a 1957 model.
It will easily retap to 120/240-1P - assuming I can locate manuals/instructions.
The NG to LPG conversion appears to be a simple matter of retuning the mixer.
If any of that is wrong, please correct me.
QUESTION - The original transfer switch is available. Should I pay to have it removed/bypassed (~$250) for my use or should I just buy a new modern TS?
If you have manuals I will greatly appreciate any and all info.
GREAT SITE HERE GUYS!!! THANKS!
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  #2  
Old 11-08-2017, 09:50:05 AM
Wayne 440 Wayne 440 is offline
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Default Re: Newbie with 30.0 EK-15R/1933D

Buy a new switch, if the original is as old as the set is.
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Old 11-08-2017, 10:44:44 AM
yellowlister yellowlister is offline
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Default Re: Newbie with 30.0 EK-15R/1933D

Was made 5 of 71. Some of the 15r voltage code sets will drop to 20 kw on single phase unless it's extended stack
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Old 11-08-2017, 10:44:59 AM
Kevin K Kevin K is offline
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Default Re: Newbie with 30.0 EK-15R/1933D

The serial number(0571300010) shows your generator was built in May (05) of 1971 (71).

Go to the Twinslan site and download the manuals: http://www.twinslan.net/~n0nas/manuals/onan/

928-0120 Operator
900-0150 generator Service
928-0220 Parts
T-105 Gaseous service manual
Check in the OEM Engine manuals folder for an engine service manual.

I'm attaching the factory production order and wiring diagrams.

Good luck.
Attached Files
File Type: pdf 300EK15R1933D.pdf (20.4 KB, 14 views)
File Type: pdf 612-4348.pdf (135.6 KB, 6 views)
File Type: pdf 612-4929.pdf (105.3 KB, 5 views)
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Old 11-08-2017, 02:06:13 PM
Mac Sine Mac Sine is offline
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Default Re: Newbie with 30.0 EK-15R/1933D

If the engine is equipped with an Impco carburetor, you will need to install a negative-feed (demand) regulator upstream of the carburetor to run LP-Gas. A "standard" Impco carburetor handling LP-Gas (Propane) fuel requires a negative 1.5-inch water column gas inlet pressure (a vacuum). Natural gas, in contrast, is fed to the Impco carburetor at positive 5 inches water column.
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Old 11-08-2017, 10:28:40 PM
ChapinGuy ChapinGuy is offline
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Default Re: Newbie with 30.0 EK-15R/1933D

Attached should be pictures of the gas supply system. It appears to me to be a gas shutoff, maybe a regulator and or course a carburetor. Is this gear comparable with LPG.

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Old 11-08-2017, 11:00:03 PM
ChapinGuy ChapinGuy is offline
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Default Re: Newbie with 30.0 EK-15R/1933D

Big thanks!!
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Old 11-09-2017, 07:53:27 AM
Max Thompson Max Thompson is offline
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Default Re: Newbie with 30.0 EK-15R/1933D

Quote:
Originally Posted by Mac Sine View Post
If the engine is equipped with an Impco carburetor, you will need to install a negative-feed (demand) regulator upstream of the carburetor to run LP-Gas. A "standard" Impco carburetor handling LP-Gas (Propane) fuel requires a negative 1.5-inch water column gas inlet pressure (a vacuum). Natural gas, in contrast, is fed to the Impco carburetor at positive 5 inches water column.
Huh?????

I would like for you to elaborate some on the information you posted above. I would like to find out more about "negative feed" regulators.
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Old 11-09-2017, 01:13:50 PM
grif grif is offline
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Default Re: Newbie with 30.0 EK-15R/1933D

Quote:
Originally Posted by Max Thompson View Post
Huh?????

I would like for you to elaborate some on the information you posted above. I would like to find out more about "negative feed" regulators.
This needs a bit more looking. I think he's mistaking or misstated the vacuum signal from the engine to start the fuel flow on gaseous regulators with the inlet pressure to the demand regulator.
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Old 11-09-2017, 02:10:03 PM
Mac Sine Mac Sine is offline
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Default Re: Newbie with 30.0 EK-15R/1933D

ChapinGuy - The "Imp" (or Maxitrol) regulator shown in your picture three is what you need to change from natural gas configuration to propane gas configuration. Your "Imp" regulator is installed with the spring tower pointing down toward the ground. For natural gas operation, the spring inside the tower is adjusted to provide a nominal 5 inch water column positive pressure at the carburetor gas inlet. For propane gas operation you unscrew the cap on the tower and remove the spring from the tower. This causes the "Imp" to function as a negative-feed regulator and it will yield a nominal 1 inch water column negative (vacuum) pressure at the carburetor gas inlet. The "Imp" has to be installed with the spring tower pointing down to do this.

Max - A negative feed regulator is a demand regulator. It does not allow gas to flow to the carburetor until a vacuum signal is applied on the outlet of the regulator. When the engine is running the fuel gas pressure to the carburetor is below atmospheric pressure, therefore, a negative pressure. The well known Garretson KN is another example of a negative feed regulator. The nominal setpoint on the KN is negative one-half inch water column.

The difference between the Impco and Garretson regulator settings relate to the respective carburetor designs. The KN is applied with a venturi type carburetor, while the Impco carburetors are an air valve design. The vacuum signal derived by a venturi carburetor is relatively weak, compared to the vacuum signal derived by an air valve carburetor.

Do not confuse a vacuum-operated fuel lock device with a negative feed regulator. They are not the same. A vacuum fuel lock is operated by intake manifold vacuum. A demand regulator is responding to carburetor venturi vacuum. These two vacuum signals are very different from one another.
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Old 11-09-2017, 08:01:26 PM
Max Thompson Max Thompson is offline
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Default Re: Newbie with 30.0 EK-15R/1933D

Quote:
Originally Posted by Mac Sine View Post
Max - A negative feed regulator is a demand regulator.
Ok. Different terminology. I am fairly familiar with demand regulators and how they operate. Though I have never heard of a negative "feed" regulator. In my little mind, you can not "feed" a regulator with a negative pressure (in the applications we normally see). Yes, a demand regulator is controlled by "negative" pressure, but not "fed" negative pressure.
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Old 11-09-2017, 09:05:45 PM
ChapinGuy ChapinGuy is offline
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Default Re: Newbie with 30.0 EK-15R/1933D

Wonderful advice guys and great news! It sounds like I have everything I need except a good sized tank and I guess the high pressure regulator. Those parts should be easy enough for my local propane dealer to spec out. Does anyone know what size tank I would need to get say 3 days of run time at around 10KW and wired for single phase?....so at 50% load there about I guess
.
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Old 11-09-2017, 09:19:39 PM
Gunny Gunny is offline
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Default Re: Newbie with 30.0 EK-15R/1933D

You are not so much concerned as to how long the fuel supply in the tank will last as yu are with surface area needed to boil off the propane to a vapor. propane boils at -44 degrees F.

A 259 gallon tank would be marginal. Mount the first regulator at the tank taking tank pressure down to 10 psi. Them run the appropriate sized line to the genset, there mount another regulator and bring the pressure down to 7 to 11" WC (Water Column) Consult that gaseous fuel manual and do this right or you will have a fuel problem when you need it most. Probably the coldest night of the year, right after an ice storm has taken the power out. The #1 problem with propane fueled gensets is the fuel system not sized and/or configured correctly.
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Old 11-09-2017, 10:26:01 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: Newbie with 30.0 EK-15R/1933D

Full load fuel consumption for propane on a 30EK is 210 Cubic feet per Hr. just for your information.
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Old 11-10-2017, 01:24:23 PM
Mac Sine Mac Sine is offline
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Default Re: Newbie with 30.0 EK-15R/1933D

Max - "Negative feed" referring to the fuel pressure entering the carburetor gas inlet being below atmospheric pressure; that is, the pressure coming out of the demand regulator.

Agreed that the supply pressure to a "negative-feed regulator" is a positive pressure.

ChapinGuy - You could also consider a propane liquid withdrawal system. That way you would not need a tank having a large vaporization surface area. You would replace the "Imp" regulator currently on your engine with an Impco EB vaporizer-regulator and also install either an electric lock-off or an Impco VFF30 vacuum lock-off in the liquid supply upstream of the EB vaporizer-regulator. The regulator portion of the EB contains both a primary regulator and the demand regulator therefore you do not need any other hardware other than the EB and a liquid lock-off. You do have to connect the vaporizer portion of the EB to engine coolant.
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