The re-circulating water system is the standard water system used on most single-wide and some double-wide presses.

This system consists of a storage tank and pump, which supplies a combination of water and fountain solution to water trays located on either side of each printing unit.

The water trays have a supply line at one end and a standpipe at the other. The water mixture is pumped from the storage tank through the supply line to the tray. The standpipe is used to prevent the water from overflowing the tray.

When the water mixture reaches the top of the standpipe the water will overflow into the standpipe and then the water will be returned to the storage tank via the drain line. So the height of the standpipe determines the water level in the water tray. This keeps the water level in the tray high enough so that water is always in contact with the dampener feed roller (see Figure 1).



Figure 1

Some pitfalls

For all its versatility, this type of system requires a significant amount of maintenance. When the water system is insufficiently maintained, ink and paper lint will collect at the low points of the return line. This is especially true since portions of the return line are at the same level as the bottom of the storage tank.

The filter in the storage tank helps clean the water mixture before it is sent back to the water trays. Unfortunately, the filter does not capture all of the debris.

Eventually, the ink blobs and paper lint will build up around the standpipe or in the tray drain line, restricting the water mixture as it returns to the storage tank. The result? The water trays overflow.

Again, since the filter can’t capture all the debris, the water tray line will also eventually plug, causing scumming on the printed page.

Sad smells

Compounding the problem is bacteria growth.

Buildup and other contamination in the return line, water mix storage tank, water tray supply line and water trays also encourage bacteria growth. This can lead to the creation of a nasty odor, particularly if the system hasn’t been used for several hours.

To protect against odors developing, this type of water system (including the water trays) should be cleaned at least once a week; twice a week if the water doesn’t remain clear or if the smell returns.

Another option is to use spraybars to protect against contamination.

Spraybar systems are very clean because water only flows out of the system and contaminated water is not returned. Contamination, in fact, can only occur if the water source or the fountain solution itself is tainted. There are no water trays or storage tanks to clean and no lines to unplug.

The non-return approach

A less expensive solution is a non-return water system (see Figure 2).



Figure 2

This is similar to a re-circulating water system except that the return line has been eliminated. The non-return water system eliminates storage tank contamination. It also eliminates water backup or slow drains, which cause overflow problems that exist with the re-circulating system.

Water tray supply-line plugging is also prevented since only fresh mixture is flowing through it. However, the water trays still collect ink and paper lint and must be cleaned regularly. This system will pay for itself as maintenance, newsprint consumption and downtime are reduced. Finally, because there are no pipes underfoot to trip up press personnel, non-return water systems are more orderly.

The non-return water system uses a float valve instead of a standpipe to maintain correct water tray levels. In some installations, a float is added to each water tray. In other installations the float valve is added to a water box that in turn is attached to the drive side of each unit; a feed line then connects the water box to each water tray. Since water seeks its own level, the water box height is adjusted so that the water level in the box is high enough to provide an adequate amount of water in each water tray.

The non-return water system can be installed by anyone, reducing the cost of installation. An inexperienced person can install the system on an eight-unit press in one day.

Frank Bourlon has more than 30 years’ experience in the newspaper industry. He is the executive and training director for the Newspaper Production & Research Center. Readers who want more information about water systems can contact Bourlon at 405.524.7774 or via e-mail at fbourlon@np-rc.org.