Knuckle joints are used between movable and non-movable pipes, and are universal joints for them. Because the surface of the ball joint and the inner ball return accurately to their original positions, no excessive force is exerted upon the pipes. Furthermore, because disc springs are used, excessive force is not exerted upon the springs even if direction is reversed, and eccentricity is taken on by the inner ball and ball washer, so the usage of the spring, with the load perpendicular, is optimal. In addition, hard chrome plating on the ball surface and Teflon seal rings give an even better seal and a long operational life.
Specification
| Fluid | Steam, Gas, Hot Water, Cold Water | |
|---|---|---|
| Maximum Operating | 3.2 MPa (460 psi) | |
| Maximum Allowable | 205℃ (401℉) | |
| End Connection | Thread (Rc, NPT) | |
| Range of Movement | Movable Type | ±6 - 10 degrees |
| Non-Movable Type | ±1 degrees | |
*For non-movable types, spacer rings are added to movable types.
Outside
| Shape of Ball Joint | |||
|---|---|---|---|
| Angle Type | Straight Type | ||
| Shape of Body | Angle Type |
 Movable Type : LJ1221-□□ Non-Movable Type : LJ1222-□□ |
 Movable Type : LJ1211-□□ Non-Movable Type : LJ1212-□□ |
| Straight Type |
 Movable Type : LJ1121-□□ Non-Movable Type : LJ1122-□□ |
 Movable Type : LJ1111-□□ Non-Movable Type : LJ1112-□□ |
|
Order Code
| Symbol | Meaning of Symbol | Meaning of number and alphabetical character |
Remarks | |
|---|---|---|---|---|
| N1 | Model Series | 1 | First Generation | |
| N2 | Body Shape | 1 | Straight type | |
| 2 | Angle Type | |||
| N3 | Ball Joint Shape | 1 | Straight type | |
| 2 | Angle Type | |||
| N4 | Range of Movement | 1 | ±6 - 10 degrees | 1: Movavle Type 2: Non-Movable type |
| 2 | ±1 degree | |||
| N5 | Port Size | 15 | 1/2" | |
| 20 | 3/4" | |||
| 25 | 1" | |||
| 32 | 1-1/4" | |||
| 40 | 1-1/2" | |||
| N6 | End Connection | P | Rc | Indicates thread for body port. |
| N | NPT | |||
| N7 | Special Options | XY | Material of Body : SUS | Body material is SCS13. (Standard FCD450) *Check specifications |
| Z□□ | Other Special Options | Indicates fixed number (Z01~) corresponding to each special option. | ||
Example of Use
A typical use of knuckle joints is provided by this dogleg piping. The dogleg piping uses three knuckle joints, and with this method movable piping in a direct line can be attached to non-movable without stress. (Figure 1)
Using this moving plane dogleg piping, liquid can be moved safely and surely in a mechanical apparatus with non-movable piping.
Points for consideration with dogleg piping
- The aperture for the piping should be set at less than 135°.
- Where the aperture is small, take care with pipe length. In some cases too great a
strain can result upon the joint or piping.
- With vertical motion dogleg piping, in cases where a Movable Type knuckle joint with
large range of movement is used, this can lead to the pipes shaking. To avoid this, use
a Non-Movable Type knuckle joint for the top joint.
- Do not use Non-Movable Type joints in two out of three joints. They will be unable to absorb
the movement of the movable pipes, and the stresses placed upon the joints and pipes may be too great.
