CA room leakage is an ongoing problem for fruit growers (and CA technicians) worldwide.
Well sealed leak tight rooms will save significantly in the operating costs of your nitrogen generator and should provide better fruit out of storage.
Currently, we are 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 much more likely to move and are much more difficult to reseal.
Construction: foam spray onto metal sheeting
Obviously, use a reputable operator and ensure you have adequate and even spray thickness.
Room penetrations
Holes in a CA room are similar to holes that are drilled 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.
Pipework
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 obviously more cost effective, the effects of strong winds on unprotected panel walls can cause the walls to flex and either—while remaining gas tight—sucks in air, or in the worst case, causes damage to the room’s internal sealing.
Extreme heat on the panel walls will usually cause damage to the paint or in some cases, delamination of the bond between the panel and foam allowing water to enter the panels.
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 the CA room walls and roof which will also assist in reducing your refrigeration operating costs.
Room sealants
ACS has used one brand of sealant for many years and has found the products to be very effective when used correctly—preparation is everything!
ACS is happy to provide general advice and we are always delighted to see more leak tight rooms, but if all else fails, ACS provides leak testing and repair products.
For information, see the September 2012 issue of Tree Fruit
