ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
IRC M1307.3
by BigB. 08/17/18 11:52 PM
Calling all Non-US members!! (Non-US only)
by Bill Addiss. 08/13/18 05:52 PM
Upgrade the old panel
by gfretwell. 08/13/18 12:20 AM
depth of duckbank
by ghost307. 08/12/18 09:26 PM
Section 179 vehicle purchases
by BigB. 08/05/18 01:06 PM
New in the Gallery:
Plug terminals
Housebilding DIY wiring
Who's Online Now
1 registered members (BigB), 6 guests, and 21 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
Very low duty cycle timer? #69221
09/02/06 12:44 PM
09/02/06 12:44 PM
N
NJwirenut  Offline OP
Member
Joined: Sep 2001
Posts: 806
Bergen County, NJ
Does anyone know of an inexpensive method of automatically turning on a small 120VAC load for a couple minutes once a week or so?

The application is an automatic water drain for an air compressor. I want to install a solenoid valve at the bottom of the tank, and turn it on once a week or so to drain out the accumulated water. The exact time of day that it actuates isn't important, and neither is the exact frequency of operation. A standard intermatic type time switch gives a minimum "ON" cycle time of 15 minutes, which is much longer than needed to blow out the water, and would waste a lot of air. I have seen digital programmable devices, but they seem like overkill for this application, with mulitple outputs and setpoints which I would never need. Time switches would also need to be reset after a power interruption, which is annoying. I am thinking of something like a time delay relay with a repeat cycle mode, but I don't know of any with such a long cycle time.

Yes, I know that there are automatic float type valves that are made just for this purpose, but we have tried several models, and they all failed shortly after installation. A solenoid valve/timer should be a lot more robust, since it isn't relying on floats which tend to bind up over time.

[This message has been edited by NJwirenut (edited 09-02-2006).]

Work Gear for Electricians and the Trades
Re: Very low duty cycle timer? #69222
09/02/06 12:58 PM
09/02/06 12:58 PM
T
Tiger  Offline
Member
Joined: May 2005
Posts: 706
Crystal Lake, IL USA
Isn't there a small tank & pump used in HVAC to pump whatever drips out of furnace/a.c. units?

Dave

Re: Very low duty cycle timer? #69223
09/02/06 01:17 PM
09/02/06 01:17 PM
J
JCooper  Offline
Member
Joined: Dec 2002
Posts: 228
Kendall Park, NJ USA
I think I know what you are looking for NJWirenut, my firehouse has the same thing on our compressor but it fires once every half hour or so for about a second. I will take a look at what is running it later today and post back.

Re: Very low duty cycle timer? #69224
09/02/06 01:34 PM
09/02/06 01:34 PM
C
circuit man  Offline
Member
Joined: Nov 2001
Posts: 273
saluda,s.c.
harbor freight sells an automatic tank drainer that is hooked up through the unloader line on the pressure switch.it empties when it comes on & when it shuts down. works pretty good. has every thing ya need in the box.some of the supply houses should have these.

Re: Very low duty cycle timer? #69225
09/02/06 02:45 PM
09/02/06 02:45 PM
I
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
I have used these electric auto drains with good success.

[Linked Image]

They did not clog up in a very damp and dirty environment.

If you must build your own I know timers that will work but they are not inexpensive. $100 - $200.



[This message has been edited by iwire (edited 09-02-2006).]


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: Very low duty cycle timer? #69226
09/02/06 04:57 PM
09/02/06 04:57 PM
C
CharlieK  Offline
Member
Joined: Mar 2003
Posts: 21
Baltimore. Md. U.S.A.
NJ. try a Intermatic C8855. It has an on renge of 21/2 seconds to 5 minutes every 24 hours and sells for about 100.00

Charlie

Re: Very low duty cycle timer? #69227
09/02/06 06:46 PM
09/02/06 06:46 PM
J
JoeTestingEngr  Offline
Member
Joined: Nov 2005
Posts: 794
Chicago, Il.
NJ, If you follow your 24 Hr />=15 min timer with any of a number of "interval on" timers, your final result would be a shorter purge every day. You could fine tune the combination any way you wanted.
Joe

Re: Very low duty cycle timer? #69228
09/03/06 10:26 AM
09/03/06 10:26 AM
I
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Joe brings up a good point about the timing.

A few seconds a day is IMO a better idea than once a week.

The electric one I posted above we might even set for 1 or 2 seconds per hour.

A quick PSSHHHHT every hour and the tank stays dry. [Linked Image]


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: Very low duty cycle timer? #69229
09/03/06 12:11 PM
09/03/06 12:11 PM
H
Helectric  Offline
Member
Joined: Jan 2005
Posts: 90
Brandon, SD
They make automatic drain valves for just this pupose. If you contact an air compressor supplier or visit their web site you should find one. Here's a link to one that is similar to those that I've used in the past. They're available in all voltages. The ones that I've used typically come equiped with a 110v cord.
http://www.generalairproducts.com/pages2/drainvlvs.html

Re: Very low duty cycle timer? #69230
09/03/06 12:28 PM
09/03/06 12:28 PM
N
NJwirenut  Offline OP
Member
Joined: Sep 2001
Posts: 806
Bergen County, NJ
Looks like McMaster-Carr carries the one Iwire posted. Will probably order one of those.

Hopefully the electric setup will hold up better than the float type.

Thanks, all!

Page 1 of 2 1 2

Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Trumpy
Trumpy
SI,New Zealand
Posts: 8,236
Joined: July 2002
Show All Member Profiles 
Top Posters(30 Days)
BigB 3
Popular Topics(Views)
248,590 Are you busy
186,323 Re: Forum
175,782 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.027s Queries: 15 (0.004s) Memory: 1.0249 MB (Peak: 1.2005 MB) Zlib enabled. Server Time: 2018-08-18 05:09:40 UTC