Useful for DIY modifications to medium-pressure hose layouts or for carrying on trips.

■ Product: Slim Monkey Wrench & 5/32 inch L.P. or H.P. Plug L-shaped Hexagonal Allen Key (1 of each)

■ Overview

The nuts used to tighten the L.P. hose (medium pressure hose) connected to the regulator (2nd stage) when attaching it to the L.P. port on the 1st stage side are of the ANSI (American National Standards Institute) inch standard. (Image 1)

Tools used for tightening and loosening bolts and nuts include wrenches and spanners. In American English, they are called wrenches, and in British English, spanners, but they essentially refer to the same tool.

In Japan, by convention, a wrench is a tool with a closed end that fits over the top of a nut, while a spanner is a tool with an open U-shaped end that grips the nut. (Image 2)

Structurally, it is impossible to attach the L.P. hose connected to the regulator to the L.P. port (low-pressure connection) of the 1st stage without using a spanner.

The nut size is listed as 9/16 in the specifications of major diving gear manufacturers. This is approximately 14mm when converted to millimeters for the width across flats. However, when using a general JIS standard 14mm wrench to tighten or loosen an inch-standard nut, there is a slight gap, causing the wrench to wobble. If torque is applied in this state, the load is concentrated on the corners of the hexagonal nut. If this continues, the corners of the nut will be damaged by the wrench, a phenomenon commonly referred to as rounding the nut, making it impossible to tighten or loosen with the wrench.

We recommend using a monkey wrench for tightening and loosening inch-standard nuts. (Image 3)

Its feature is that the opening width of the jaws can be adjusted using a screw-type worm gear, allowing it to accommodate various nut sizes up to its maximum opening width without needing to change tools.

However, general monkey wrenches (Image 3, bottom of Image 4) have large tips. Even when the hose protector attached to the L.P. hose is shifted to tighten or loosen, there is a risk of accidentally hitting the 1st stage with the tip of the monkey wrench, causing scratches. This can damage the plating on the 1st stage surface, exposing the underlying brass (galling).

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