Boom hydraulics replacement - twin line or two singles?

[Andy_]

Hey guys, long time lurker, first time poster.

Anyway, I'm getting ready to re-run the boom hydraulic lines on my 1989 Grove AMZ-66 Manlift, as the originals have finally seen too much sun (polymer braid is showing at the elbows) and could soon fail.

My question is this: Why should I pay extra for twin hydraulic line instead of using two singles? There are actually two 1/4" (dash 4) twin lines running the length of the boom (bucket tilt and rotate) and over that 80-foot length, they are either held to the inner "ceiling" of the boom, or nicely kept within the drag chain, but either way, they don't seem likely to get out of position with use - even if they were singles. I can imagine that Grove maybe used twin line for ease of assembly/service, but 1/4" twin line comes at a premium (only the Parker low-temp 55LT line is available in 1/4" twin) and is not well stocked. There are a lot more choices for single line, including the type that fits the Parker Mini Crimp that I have free access to. The mini crimp would allow me to cut to final length and terminate in-situ without buying another couple hundred bucks worth of crimp adapting die. There are other similarly-sized (electrical) lines in this same path, and they aren't bundled in any way.

So, what's the big deal with twin line? Does it stay put better, have better "response" due to the anchoring to a low pressure line, or just look prettier? There's also some risk in separating the pair into halves for termination - one slip of the utility knife and I've just made an 80-foot length too short.

Thanks in advance, and Happy New Year!
Andy_

 

[Moonlite]

My opinion is the twin line adds some strength to the line. Not as in burst pressure, but in the line being not able to drop or move side to side as much.

 

[Andy_]

Thanks for the reply, Moonlite. I can see that, however in this case the only places where it's free to move and/or droop, it's already split into single lines - except at the two elbows. I imagine some quality zip ties would be equally effective against movement in that total 6 feet of length. Incidentally, it's looking like about a $600 price difference ($1600 vs $2200) for the singles vs twin solutions.