vacume

jaybee

What is the meaning of vaccume on oil burners.Can anyone explain it to me whats a good vaccum reading,whats bad,and what does it signafies?

Unknown

Yes

Go to this site...

http://oiltechtalk.com/

Click on "Just for Teks"

In the Industry Technical Bulletins, click on Oil Burners.

Then on Calculating Vacuum.

Lots of stuff there (Thanks John!!!), browse around.

Here's some.



Calculating Vacuum

To determine the vacuum draw that will be produced you can use this simple formula:

V = LFQ + 0.75H

Where: V = Vacuum in inches of HG, L = Total Line Length in Feet, F = Line factor from table, Q = Total Oil Flow in GPH, and H = Total Lift in Feet (number will be minus when burner is below Tank)



Copper Size Factor

3/8" O.D 0.0086

1/2" O.D. 0.00218

5/8" O.D. 0.000785


From the "Suntec Installation And Service Manual"

To calculate the Vacuum Draw for a Single-line installation use the formula above and "Q" will be the actual firing rate (GPH). When measuring the line length one must add one foot of length for every elbow, oil valve and oil filter. Do not include check valves or OSV's as a check valve will add about 1 inch of vacuum to a system and should be added later.

To calculate the Vacuum Draw for a Two-line installation use the formula above and "Q" will be equal to the actual flow (GPH) in the line or the value of the Gear Set. All fuel pumps, regardless of manufacture have a gear set that determines the amount of oil a pump will pump. This gear set will vary from model to model. You can get this value from the Pump manufacturer. When measuring the line length one must add one foot of length for every elbow and oil valve. Do not include check valves or OSV's as each check valve will add about one inch of vacuum to a system and should be added later. For oil filters I add three inches of vacuum which will go up as the filter gets dirty. The high vacuum draw for oil filters is due to the fact that the filters we use are not designed for the flow rates of a two pipe system.

We strongly recommend that a single-line system be used whenever possible in fact I do not install two-line systems any more but use a device called a Tiger-loop instead. A Tiger-loop is an ingenious device that gives the advantages of a two line system while remaining single-line. But if you must install a two-line system we recommend that you use a larger line size.

Another consideration is the fact that that these calculation will give you the vacuum draw for clean oil lines only. There is now way to determine the vacuum draw once the line start to muck up.

Do to the fact that you won't easily get the information from Riello we will include it here, there 3, 5, & 10F fuel units all have a 15 GPH Gear Set. The Gear Set in their larger units is 20 GPH.

In order to keep your customers happy keep the vacuum draw as low as possible.

JCG

john_35

vaccum=load

The simple answer is vaccum equals load on the fuel pump and drive motor. The higher the vacuum reading the harder the pump has to work to maintain 100 psig at the discharge port (and nozzle). It's a measure of negative pressure. Think of a straw in a milkshake. The thicker the shake the harder you have to suck on that straw. If you use a bigger straw (like the one you get at McDonalds) it's easier to drink that milkshake. That's why you're better off with half inch line than three-eigths. Vaccum also increases with the rate of flow. That's why one line is better than two, up to a point. Two lines help you lift the fuel if the burner is higher than the tank, but on the downside they tend to make the filter clog up because the flow rate becomes whatever the capacity of the pump is (usually 22 gph for most minis). That's a lot of oil to be running thru your filter all the time. Didn't used to be a problem back when all fuel was distilled instead of catalytically cracked like it is today.(But that's a whole other story.) Anywho, the simple rule is "filter only what you use". And try not to lift any higher than you need to.

jaybee

vacume

Thanks once again guys!