CA room leakage is an ongoing problem for fruit growers (and CA technicians) worldwide.
Well sealed, leak-tight rooms save significantly in operating costs for nitrogen generation, and should provide better fruit out of storage.
We are currently discussing several new projects with customers, so I think it is timely if you are building new rooms, to consider the following.
Construction—panel rooms
Building rooms on top of a finished concrete floor versus the more traditional method of taking the walls down to the subfloor and then installing insulation/wear floor on top.
The latter is more expensive but in our experience will result in rooms that are much less likely to leak at the floor–wall joint.
Walls finished on top of the floor, even when a concrete kerb is installed, are more likely to move and are much more difficult to reseal.
Construction–foam spray onto metal
Use a reputable operator and ensure you have adequate and even spray thickness.
Room penetrations
Holes in a CA room are similar to holes in boats—try to reduce the number and make sure they don’t leak.
Some holes are necessary, but ensure that your contractors understand the importance of effectively sealing all penetrations and also look for methods of reducing the number of penetrations.
In automatic control systems—to ensure effective control—we have two sets of pipework that need to be connected to each room. We redesigned the room connections to reduce the penetrations to two.
Do a quick count of how many penetrations have been installed in your new gas tight CA room, you may be surprised how many there are. Can you reduce the number or share one penetration for all wiring—for example, fan wiring, thermostats, and temperature probes?
CA room protection from the weather
Some installations only have a roof over the rooms with short wall sections immediately under the roof.
While this is more cost effective, the effects of strong winds on unprotected panel walls can cause the walls to flex and either (while remaining gas tight) suck in air, or in the worst case, cause damage to the room’s internal sealing.
As seen recently, we are experiencing some extreme weather conditions and I think the idea of exposed panel walls needs to be reviewed in light of the storm conditions experienced during early February in most areas of Australia.
Extreme heat on panel walls usually damages the paint and in some cases results in delamination of the bond between the panel and foam.
Well designed buildings with passive air flows i.e. through a gap at the bottom of the outside walls and vented through the roof, can reduce heat load on CA room walls and roof, and assists in reducing refrigeration operating costs.
Room sealants
ACS has used one brand of sealant for many years and has found these products to be very effective when used correctly—preparation is everything!
Advice
ACS is happy to provide general advice and we are always delighted to see leak-tight rooms. However, if all else fails ACS provides leak testing and repair products.
For more information and contact details see the March 2012 issue of Tree Fruit
