A hose that keeps blowing off its barb, or that weeps a drop every few seconds right at the fitting, is almost never a bad hose. It is a barb that is the wrong size for the hose, a clamp in the wrong spot, or a fitting that is not rated for what the pump puts out. The trick is to measure before you reach for a bigger clamp.
Depressurize and drain the line first, and wear gloves; a hose that lets go under pressure sprays whatever is in it.
1. Find out why it is letting go
- Hose slides off with the clamp still tight — hose ID is larger than the barb. A 1" hose on a 3/4" barb will never hold; the clamp just crushes the hose around a barb it cannot grip.
- Hose is split at the end or the barb tears it on install — hose ID is smaller than the barb, or the hose was forced on cold. Warm the hose end or go down a barb size.
- Weeps at the barb only under pressure — clamp sits behind the barb ridges instead of over them, or a single worm clamp on a 1-1/2" or 2" line that needs a T-bolt.
- Weeps at the thread end, not the hose end — thread sealant or a cracked poly fitting from overtightening. Different fix; see below.
- Fitting itself cracked or swelled — fitting is under-rated for pressure, or the wrong plastic for the chemical. Nylon swells with water and some fertilizers; glass-filled polypropylene does not.
- 90° barb snapped off at the elbow — hose weight or boom whip is loading the fitting sideways. Support the hose or use a sweep.
2. Why it fails
Barb fittings hold by stretching the hose over ridges and letting the clamp keep it there. That only works when the hose ID matches the barb nominal size, the clamp band is over the barbed section, and the fitting can take the pressure. Banjo's glass-reinforced polypropylene barbs (the HB series) are listed at 300 psi, and the HM hose menders at 300 psi, in a -20 to 150°F range. Hypro's A34 and A3812 barbs are nylon, which is fine for water and most spray mixes but will soften and swell in some fertilizers and solvents. Stainless barbs cost more and take the most pressure, but they are heavy and will crack a poly fitting if you overtighten them into it. Pulsing from a diaphragm pump and boom whip loosen clamps that were tight at the shop, and UV makes old EPDM hose hard so it no longer grips.
3. The part for your line
| Hose / situation | Fitting |
|---|---|
| 1/2" hose, 1/2" MPT port | Banjo HB050 straight, HB050-90 elbow |
| 3/4" hose, 3/4" MPT port | Banjo HB075 straight, HB075-90 elbow, or nylon Hypro A34 |
| 1" hose, 1" MPT port | Banjo HB100 straight, HB100-90 elbow |
| 1-1/4" hose | Banjo HB125 straight, HB125-90 elbow |
| 2" hose, 2" MPT port | Banjo HB200 straight, HB200-90 elbow |
| 3" hose | Banjo HB300 straight, HB300-90 elbow |
| Stepping down: 3/4" port to 1/2" hose, 1" port to 3/4" hose | HB075-050, HB100-075, HB100/075-90 |
| Stepping up: 3/4" port to 1" hose, 1" port to 1-1/4" hose | HB075-100, HB100-125 |
| 3/8" hose off a 3/8" or 1/2" port (gauge and agitation lines) | HB038, HB050-038, HB038-90, or nylon Hypro A3812 (3/8" MNPT x 1/2" barb) |
| Tee into a hose run | HBT075, HBT100, HBT200, HBT075-050 reducing tee |
| Splice a cut hose | HM050, HM100, HM125, HM150, HM200, HM300 |
| Off a Banjo manifold flange instead of a thread | M200BRB, M200BRB90, M220BRB, M100BRB90 |
| Clamps for 1-1/2" to 3" hose | T-bolt TC181, TC193, TC231, Banjo TC331 |
4. Putting it on so it stays on
- Measure the hose ID with calipers, not the printing on the jacket. Suction hose is often a true 2", pressure hose a hair under. Buy the barb to the ID you measured.
- Push the hose on until it bottoms against the fitting shoulder. Warm stiff hose in hot water; do not use oil or soap, it stays slippery.
- Put the clamp over the barbed section, about one band width back from the hose end. A clamp hanging off the end of the barb holds nothing.
- On 1-1/2" and larger pressure lines use a T-bolt clamp. On high-pressure or pulsing lines, two clamps with the screws on opposite sides.
- Retighten after the first day of use. Hose takes a set and clamps loosen.
- Use 90° barbs where the hose has to turn right at the fitting, but support the hose within a foot so the elbow is not a lever arm. For a long turn in a big line, a flange sweep like the M200SWP90 is kinder to the pump.
- A hose mender is a fine permanent fix for a cut or a blown end on a straight run. It is not a fix for a hose that is cracked along its length or chalky from UV; replace that hose.
- On the thread end, use PTFE tape on poly male threads and go hand tight plus a turn. If a poly barb cracks at the hex, it was overtightened or wrenched on a stainless fitting.
Not sure which barb or hose? Send a photo of the fitting, the clamp, and a tape measure across the hose end to sales@spraycenter.com or call (509) 838-2209.
Spray Center Electronics stocks Banjo, Hypro and Green Leaf hose barbs, menders and clamps in Spokane, WA. Part numbers here come from the manufacturers' parts sheets; if your fitting does not match what is described above, send a photo and we'll match it before you order.