Geoff,
Aster instructions for the Mikado just state that the working pressure is between 3 and 4 bar. There is no mention of maximum boiler pressure. The instructions are inconsistent as to what pressure reading the safety valve should vent. The instructions inconsistently provide that the safety valve should vent at 3.0, 3.5 and 3.5 to 4.0.
Thanks, Joe
On Jan 10, 2005, at 5:54 PM, Geoff Spenceley wrote:
Joe,
Usually the Aster instructions list the ratings for the max boiler pressure and working pressure.
As for whistles, I steam Brit locos and their whistles are usually like gnat farts--Peep. Peep!
Geoff.
Geoff,
Thanks! My new one adjusts nicely. Now, I understand the point of the paint on the safety valve. I am going to tweak it so it vents between 4.0 and 5.0 bar. I was reading the SitG article about adding a whistle to the mikado. The article recommends 5.0 bar for the optimal whistle sound; though, a good whistle sound can be achieved at half that per the article. Perhaps, 5.0 bar might be a maximum setting. After Diamondhead, I will email Aster Hobby USA for their answer.
Thanks, Joe
On Jan 9, 2005, at 5:31 PM, Geoff Spenceley wrote:
Joe,
Yes, you are on target-- the two slots-which are also the vents, are used to tighten the spring. I use strong tweezers or needle nose pliers but a home made tool would be preferable. Tighten clockwise as that compresses the spring and raises the pressure at which the valve vents.
Geoff,
How do you adjust the safety valve? Do you insert a tool of some sort into the two slots on top that are opposite each other and turn? Does a clockwise turn raise the pressure at which the safety valve vents?
Thanks, Joe
On Jan 9, 2005, at 3:50 PM, Geoff Spenceley wrote:
Joe,
I have found it necessary to adjust safety valves over the years. Aster are usually simple. Sometimes the adjustment is for cleaning, sometimes because the seal ( usually a bit of paint) deteriorates and the valve adjusting "nut" starts to unscrew. I don't know the pressure relief for a Mikado safety but I suspect about 3.5 to 4 bar is good. I usually test straight from an airline with an accurate pressure gauge in the line and adjust accordingly. Then I install the valve and air test the boiler, then the steam test, If all is OK on the steam test, I seal the adjusting nut with a touch of enamel paint, usually red.
Geoff.
Hello,
I ran the Mikado for a few hours today. My three year old was not happy with it running in reverse mostly. I tried to explain that I have to break it in again in both directions - it just wasn't working with her. Oh well.
Anyway, I installed two new safety valves because I had to replace two that were releasing steam at 2.0 and 2.5 bar. One of the new ones is releasing steam at 3.5 bar. Is there any way to adjust? My understanding is that adjusting is a bad idea. And what is the optimal pressure for these Mikado safety valves to start venting?
Thanks, Joe
