Courtesy of Kathleen at Dive Rite

In 1982 there were few manifolds available. Sherwood and ScubaPro commanded most of the market with Sherwood’s dual outlet metal-to-metal seal manifold and ScubaPro’s double barrel o-ring seal manifold. Manifolds during this period did not have centre isolation crossbars. The centre-to-centre spacing on these manifolds was 8.25-inches for aluminium 80s and steel 72s, which was tight for the increasingly popular 8-inch diameter tanks. The tight spacing meant bolts could rub against the tanks and the bands were prone to gapping.

In the late 1980s, new manifolds entered the market with a variety of new seals, which meant there were a greater variety of centre-to-centre spacing manifolds available. At this time, specialty tank band manufacturers began entering the market and offered a variety of bands to use with various manifolds and on different size tanks. Some manufacturers chose to use tack welds that would allow the bands to flex in accordance with the size of the tank, rather than manufacture multiple sets of bands.

By the 1990s, manufacturers began to standardise manifold centre spacing and centre isolation crossbars became the norm. Tack welding became obsolete and bands standardised at 7.25-inches and 8-inches. ScubaPro’s classic double barrel seal became the preferred model, providing better shock absorption, plus redundancy over the metal-to-metal seal manifolds. Today, the new 8.5-inch centre-to-centre spacing manifolds provide up to 0.25-inches of adjustability so that tank bands fit properly.

Dive Rite offers both 200 bar and 300 bar manifold valves with a 180mm isolation crossbar that fits both 7.25-inch and 8-inch diameter tanks. Bands are available in a 2.5-inch width for 7.25-inch tanks and a 3-inch width for 8-inch tanks. All Dive Rite bands are tungsten inert gas welded (TIG) and have deburred edges that minimizes scratching on painted tanks during assembly. Dive Rite bands are constructed of 18-gauge, 304 stainless steel, with a #3 polished finish and 11-gauge, 304 stainless steel structural plates. Every band is precision sheared and punched and goes through a stringent quality control test during each step of the manufacturing process.

An often heard debate is that of a threaded bolt versus an all-thread bolt and which one is better? The answer is neither. The core diameter of both a threaded bolt and an all-thread bolt is where the bolt derives its strength. A 5/16 threaded bolt and a 5/16 all-thread bolt are nearly equal in tensile strength. The tensile strength of a 5/16 threaded bolt is 85,000 psi where a 5/16 all-thread bolt is 75,000 psi – not a big difference in the world of diving. What can be important is the grade of stainless steel; bolts should be made with a high grade of stainless steel, which can better resist rusting in saltwater. Dive Rite uses 304 stainless steel, a high grade, low carbon metal. As for all- thread bolts being cheaper – they are. However, manufacturers typically choose to use all-thread bolts not due to price, but in order to provide customers with the option to customise their bolt to the desired length. If a backplate is deep, it is possible to have too many threads causing the bolts to puncture a drysuit or wetsuit. Also, some divers add trim weight to the back of their tanks, again needing the length of all-thread bolts.

Before selecting tank bands, find out if your double o-ring seal manifold was manufactured within the last five years. If so, you should not need a specialised tank band. Divers who dive manifolds without redundant double barrel o-ring seals OR manifolds manufactured more than five years ago will need to consult their manifold manufacturer for a recommendation on proper tank bands.