drain the air tanks?

Air tanks must be drained regularly, and the discharge observed for abnormalities. Some moisture may be discharged from the supply tank. A much smaller amount of moisture may be discharged from the remaining air tanks. A significant quantity of moisture being discharged from the supply tank — even when the tank is drained on a regular basis — may be normal. Discharge of a significant quantity of moisture from the remaining air tanks is not normal and should be reported.
While a small amount of oil may be found in the supply tank, any visible quantity of oil should be reported or repaired. When oil is found in any other air tank, there is risk of air brake system contamination, and the condition must be reported.
When there is a sudden increase in the amount of moisture or oil drained from any tank, the condition must be reported and repaired. Any malfunctioning drain valve must be repaired.
The supply tank should always be drained first to prevent accumulated moisture in the supply tank passing farther into the system. Drivers must know the location of all air tanks and drains.
It is important to note that the body design and suspension of some vehicles may limit safe access to the air tanks and drains unless the vehicle is supported on a hoist, or is over a pit or ramp.
Step-by-step procedure

1. Ensure that the air brake system is within its normal operating pressure range.
2. Locate and drain the supply tank until the valve discharges only clean air.
3. Locate and drain the remaining air tanks.
4. Watch the discharge from each air-tank and ensure that all air-tank drain valves function properly.
   
   Remember also that trailers will have an air supply tank as well. Most of your older trailers have long lost any cable to pull to release the air, and to be honet a lot of them do not even have this type of release. They may have a manual valve called a (petcock) you will have to crawl under trailer and manually turn the valve "OPEN" slightly and see if moisture is being release. If so let it continue to "drain" util you no longer see moisture coming out.
   
   Trailers have a small tank locate underneath them located around the axles.
   
   
   Also this same type of tank and petcock release may be located on the truck as well. Do not assume that if you do not see a cable to pull that there is no manual release for these tanks. Keeping these drained can possibly save you a lot of headache in the winter months. It's a pain in your day if you end up with moisture frozen in your air lines!
   
   
   "MY TWO CENTS"

 

I saw someone posted you never have to drain the air tanks... seriously wrong!

First, it will help keep moisture out of the system, and your brakes will be less likely to freeze in cold weather. Get used to doing it at least daily. However, on the newer trucks with DEF systems, you MUST drain the air tanks- and I'm sure that's why your carrier says do it twice daily. A little compressed air is used to shoot the DEF fluid into the catalyitic converter. If moisture gets in there, it will start to crystalize the fluid, and can cause really expensive repairs, derating your engine in the middle of the boonies, and perhaps even an expensive tow. My carrier is constantly harping on the guys with the newer trucks to drain the air tanks because of this.

 

I was taught back in the day to drain them at the end of the day. The company I worked 7 years for said no need to do it.
That said, it can't hurt to do it periodically regardless of the air dryer especially if you haven't serviced the air dryer regularly. You will get some moisture out and that's always good to do. Drain it twice a day? Hell no. That's just not necessary.
I'm in the habit of doing it once a week now with my own truck and service the air dryer every fall.

 

Imo it really depends on the truck. Most I've driven would get a bit over moisture every few days even in the summer. The Cascadia I have now never ever has any at all even in the cold. Then there was my last 9400... I swear that thing would cough out a quart a day in the Sahara.

 

Hilarious!

 

Oh yeah? Talk to our maintenance department... they'll tell you otherwise. It's rather expensive to replace the DEF system.

 

Personally I drain the tanks whenever I fuel. Mainly as that's because the cables are mounted right behind the fuel cap.

-Steven

 

What seems contrary to logic, tanks need to be drained more in colder temps when there is less moisture in the air.

But that is when a small amount of moisture can freeze and cause problems.

Mikeeee

 

If you can't find the petcocks on the tanks, disconnect your trailer emergency air (the red line), and hold the trailer supply knob (again, the red one) in, and you can do it that way.