Acrylic Expansion?

[Sean Irwin]

I'm designing a refugium/ filter area and what to make sure that I leave sufficient room to allow for the acrylic panel to expand. Is 1/8 of an inch for each side too much or too little? Thoughts? Comments? Suggestions?

Thanks,
SI

 

[Jim Tansey]

1/8 of an inch on each side should be more than enough, I fit them tight. Its not like the temperature while cutting will be much different than the service temperature.

Jim

 

[sciknen]

Can someone explain this... i didint know panels expanded?

 

[Jim Tansey]

Most materials expand when heated (grow in all dimensions), some more than others such as glass is very low expansion and plastic much higher. It should be of no concern when dealing with smaller parts and limited temperature changes as we do in the aquarium industry. Now if you were designing very long structures like bridges and railroad tracks, it must be factored into the design, as the length will grow on hot days and contract on cold days. Special joints are usually used you may have heard the term "expansion joint".

Jim

 

[JohnK]

Heat is not the issue with acrylic, water absorbtion is.

Believe it or not, acrylic does absorb some water and it swells a bit when it does. I know of at least one person in the club who had a tank crack because of this.

IME 1/8" should probably be plenty of space. If you want a better answer try asking in the acrylic fabrication thread on RC. James knows everything about acrylic.

Ask here; http://www.reefcentral.com/forums/showthread.php?s=&threadid=1056956&perpage=25&pagenumber=40

 

[Sean Irwin]

Heat is not the issue with acrylic, water absorbtion is.

Believe it or not, acrylic does absorb some water and it swells a bit when it does. I know of at least one person in the club who had a tank crack because of this.

IME 1/8" should probably be plenty of space. If you want a better answer try asking in the acrylic fabrication thread on RC. James knows everything about acrylic.

Ask here; http://www.reefcentral.com/forums/showthread.php?s=&threadid=1056956&perpage=25&pagenumber=40

Thanks Jimmy, I'll definitely check that out.

 

[marco67]

Can someone explain this... i didint know panels expanded?

Heat is not the issue with acrylic, water absorbtion is.

Believe it or not, acrylic does absorb some water and it swells a bit when it does. I know of at least one person in the club who had a tank crack because of this.

IME 1/8" should probably be plenty of space.

I've had it happen more than once when using acrylic baffles in a glass tank,
The anal in me always used to want to make nice snug joints but after (3 that I can think of) cracked tanks I learned better.

I'll second the 1/8", what I do is just mark the panel the the inside dimension of the tank and "take the line" when cutting so about a blade width or ~1/8".

For stability I cut 1" strips and silicone them on the flat as gussets for the baffle to "float" between.