A double wire hose clamp size chart only works if you read it against the right number: the outside diameter of the hose measured on the fitting, over the helix crest, where the two wires will sit. Pick the clamp whose range puts that reading in its upper half, so the screw still has travel left after the hose beds in.
This page is a field card for the pump yard: a checklist you can tape inside a service truck door, then two charts (published maker ranges, and 1 in to 6 in suction and discharge hose), then what charts leave out: helix, corrugated and layflat measuring, four worked examples, and between-sizes choices.
OneTouch Exim does not stock double wire clamps. We export worm gear, T-bolt, hi-torque, constant torque, lined and V-band clamps, so each example below names the closest OneTouch part, and the clamp cross-reference index can match a part number you already use.
Field card: measure, then match
Seven steps, in order. Each one says what to measure, with what tool, and where on the hose.
- Fit the hose first. Push the hose fully onto the shank, camlock tail or barb it will live on. Never size a double wire clamp from a loose hose end; the shank stretches the wall and moves the helix outward.
- Mark the clamp zone. With chalk or a paint pen, mark where the two wires will sit: fully over the shank, clear of the hose end and clear of the shank’s last barb ridge. That band, roughly the width of the clamp, is the only place your measurement counts.
- Measure the outside, over the crests. Wrap a pi tape (or a strip of paper and a ruler) around the marked zone, sitting on top of the helix crests. Read diameter directly from a pi tape, or divide the paper circumference by 3.1416.
- Take a second reading in the valley. On helix hose, also note the diameter between two crests. The gap between crest and valley tells you how much the wires will have to bridge or sink.
- Repeat at 90 degrees. Shanks are not always round after years of use, and suction hose ovalises. Use the larger of the two crest readings.
- Write it down in both units. Note millimetres and inches on the card. Double wire clamps are sold in mm steps in Europe and Asia and in fractional inch steps in North America, and conversion errors at the counter are common.
- Match to the upper half of a range. Choose a clamp whose minimum is at least 2 to 3 mm below your reading and whose maximum is at or just above it. If no single size does that, read the between-sizes section further down.
The general technique is in our guide on how to measure hose clamp size.
Double wire hose clamp size chart from published maker ranges
No single standard governs double wire clamps the way DIN 3017 governs worm drive clamps, so no universal double wire hose clamp size chart exists. Each maker sets its own steps, wire size and screw. Three distinct products share the name, and they size differently:
- Screw-type double wire clamps (the pump yard clamp): a loop of wire doubled back on itself, with the two free ends drawn together by a screw through a small bridge or swivel nut. Ranges are narrow, often 3 to 6 mm per size.
- Self-compensating spring double wire clamps: hardened spring wire wound twice around, opened with pliers and released onto the hose. No screw. Very narrow ranges, sized to a nominal hose OD in thousandths of an inch.
- Twin ring bolt clamps: heavy, thick-wire versions with a hex bolt, used on large suction and ducting hose.
The double wire hose clamp size chart below samples published ranges from each type. It is a sample, not a full catalogue; each maker’s table is linked under it.
| Maker and type | Sample range (mm) | Sample range (in) | Wire | Screw or drive |
|---|---|---|---|---|
| EFC double wire screw clamp with swivel nut (part 15102100) | 23.9 to 26.9 | 0.94 to 1.06 | Two 12 gauge wires | 5/16 in hex head |
| EFC, same series (15102106) | 28.4 to 31.8 | 1.12 to 1.25 | Two 12 gauge wires | 5/16 in hex; 20 to 25 in-lb install torque listed |
| EFC, same series (15102130) | 46.0 to 50.8 | 1.81 to 2.00 | Two 12 gauge wires | 5/16 in hex |
| EFC, same series (15102216) | 59.4 to 65.0 | 2.34 to 2.56 | Two 12 gauge wires | 5/16 in hex; 40 in-lb ultimate torque listed |
| Rotor Clip DW-4.5 (spring, self-compensating) | 7.0 to 7.5 | 0.274 to 0.294 | 0.039 in nominal | None (pliers) |
| Rotor Clip DW-7 | 11.0 to 11.2 | 0.432 to 0.442 | 0.059 in nominal | None (pliers) |
| Rotor Clip DW-12.5 | 19.6 to 20.6 | 0.772 to 0.812 | 0.078 in nominal | None (pliers) |
| Twin ring bolt clamp, light wire (McMaster-Carr listing) | 43.7 to 48.8 (wire band) | 1-23/32 to 1-15/16 | 3/16 in | Hex bolt, 9/16 in head |
| Twin ring bolt clamp, mid wire | 46.5 to 96 (wire band) | 1-27/32 to 3-25/32 | 1/4 in | Hex bolt, 9/16 in head |
| Twin ring bolt clamp, heavy wire | 97.3 to 210.3 (wire band) | 3-27/32 to 8-9/32 | 5/16 in | Hex bolt, 11/16 in head |
Sources: the EFC International double wire screw clamp listing (25 sizes from 0.94 in to 2.56 in in its first page), the Rotor Clip DW product pages, and the McMaster-Carr twin ring hose clamp category. Four patterns are worth noticing.
Ranges are narrow, so the measurement has to be good
The EFC series steps by about 1/16 in, and each clamp spans only 0.12 to 0.22 in (roughly 3 to 5.6 mm). Our 4SS0048 worm gear clamp covers 2.56 to 3.50 in in one part. A double wire clamp leaves little room for a sloppy reading, hence measuring on the fitting.
“12 gauge” needs a second question
EFC lists two 12 gauge wires without naming the gauge system: about 2.05 mm by American Wire Gauge, nearer 2.7 mm by steel wire gauge. Ask suppliers for wire diameter in millimetres.
Spring double wire clamps are not a pump yard part
The Rotor Clip DW line is a self-compensating spring clamp, and Rotor Clip itself positions it for lower clamping force than its single wire clamps. Ranges are tiny (DW-7 spans one hundredth of an inch). They suit small coolant, vacuum and fuel return lines, not 3 in suction hose; they are charted because buyers often order them by mistake.
Screw size climbs with diameter on metric clamps
European W1 (zinc-plated steel) wire clamps from about 35 to 105 mm are commonly listed with M6 screws that lengthen as the clamp grows, for example M6 x 40 on 35 to 40 mm and M6 x 60 on 98 to 105 mm in one pump retailer’s listings. Treat that as typical, not standard. Where no wire or screw size is published, the range on the bag is the only spec you get.
Clamp range by hose size: 1 in to 6 in suction and discharge
Most pump yard requests start with a nominal hose size (“I need clamps for 3 inch suction”). Nominal size is the inside diameter. The clamp needs the outside diameter, and that depends on wall thickness and helix profile, which vary by maker and duty rating. The chart below uses published outside diameters from Kuriyama’s Tigerflex WST heavy duty suction and discharge hose and its WH standard duty liquid suction hose, plus the WG series where available, to show how far OD moves within one nominal size.
| Nominal hose ID | Published OD examples (in) | Typical OD band, approx. (mm) | Suggested double wire range to look for (approx.) | OneTouch alternative to check |
|---|---|---|---|---|
| 1 in | 1.22 (WH, standard duty) | 31 to 36 | 30 to 35 or 32 to 36 mm, chosen after measuring on the shank | 4TB0125 T-bolt (1.25 to 1.44 in) or 4SS0016 worm gear |
| 1-1/4 in | 1.54 (WH) | 39 to 44 | 38 to 43 or 40 to 45 mm | 4SS0024 worm gear (1.06 to 2.00 in) |
| 1-1/2 in | 1.80 (WH), 1.85 (WG), 1.95 (WST) | 45 to 51 | 44 to 48 or 48 to 52 mm | 4TB0163 or 4TB0175 T-bolt |
| 2 in | 2.32 (WH), 2.40 (WG), 2.60 (WST) | 58 to 68 | 60 to 65 or 65 to 70 mm, depending on hose | 4ST250H spring T-bolt (2.50 to 2.81 in) |
| 3 in | 3.64 (WG), 3.62 (WST) | 91 to 96 | 90 to 95 or 95 to 100 mm | 4SCH412 hi-torque (3.25 to 4.13 in) |
| 4 in | 4.76 (WG and WST) | 120 to 126 for PVC helix; rubber slurry hose larger | 120 to 125 or 125 to 130 mm; heavy wire | 4SCH512 or 4SCH562 hi-torque |
| 6 in | 7.17 (WST) | 180 to 186 for PVC helix | Twin ring or heavy double wire around 180 to 190 mm | 4SCH762 hi-torque (6.75 to 7.63 in) |
The 2 in row spans about 7 mm between standard and heavy duty hose of the same nominal size, more than a typical screw-type double wire clamp’s whole range, so “2 inch clamp” is not a usable order. Published OD is also for hose off the fitting; a shank adds stretch. Rubber slurry hose has no figure here on purpose, because wall thickness varies too much between makers to guess.
For worm gear and T-bolt equivalents by size, our hose clamp size chart in mm and inches lists SAE numbers and ranges across all families.
Measuring helix and corrugated suction hose for wire clamps
Helix hose (rigid PVC spiral in a softer wall) and corrugated hose have two outside diameters at once, which is where most double wire sizing goes wrong.
Over the crest versus in the valley
The crest is the top of the helix rib; the valley is the softer wall between ribs. Size the clamp to the crest diameter. A wire clamp closes as a ring, and it cannot reach the valley until it has flattened or pushed past the crests on either side. If you size to the valley, the clamp will bottom out on the crests before it seals the valley wall, or you will fight to get it over the hose at all.
Record the valley reading too. A few millimetres of crest-to-valley difference is normal; a large one means the wires ride on rib tops with an air path under them, a leak risk on suction.
Where the two wires should sit relative to the helix
The helix runs at an angle, and a double wire clamp has two parallel rings. Kuriyama makes a dedicated spiral bolt clamp for this hose because, as its SDBC product page explains, a clamp that follows the helix can seal between the convolutions. A double wire clamp cannot follow the spiral, so you place it to do the least harm:
- Both wires go fully over the shank, never past its end. A wire sitting over the unsupported hose beyond the shank just pinches the hose.
- Keep the inner wire clear of the hose cut end by a few millimetres so it does not roll the end off.
- Rotate the clamp so the screw bridge sits on a valley if possible, not straddling a rib. A bridge on a rib rocks, and a rocking bridge loosens.
- On a shank with barbs, position the wires between barb ridges or just behind the last one, so the clamp pushes the hose into the shank’s grip rather than riding on a ridge.
- On suction hose 3 in and above, two clamps (or one clamp of a heavier design) are common practice. Kuriyama itself calls for two or more of its spiral clamps from 3 in ID up. Our article on double clamping hoses covers spacing and orientation.
Flattening on the shank
When rigid helix hose is forced onto a shank, the helix opens up and the ribs over the shank partly flatten. The crest diameter over the shank is usually larger than the published OD, while the crest-to-valley difference shrinks. This is the main reason the field card says to measure with the hose fitted. If you warm the hose end to ease it on, let it cool before measuring.
Corrugated pool and vacuum hose behaves the other way: soft ribs crush under the wires. Size to the crest, expect the clamp to close toward the low end of its range, and do not overtighten.
Measuring layflat discharge hose
Layflat comes off the reel flat, so there is no round diameter to measure until it is on a fitting. Two methods work:
- Best: measure on the shank. Fit the layflat over the shank, then pi tape the outside where the clamp goes. Layflat stretches noticeably over a shank, so this is the only reading that tells you what the clamp sees.
- Estimate from the flat width. Lay the hose flat and measure across it edge to edge. That width is half the outer circumference, so the round outside diameter is about flat width x 2 / 3.1416. Example (illustrative): a flat width of 80 mm gives an outside diameter of about 51 mm before it goes on a shank.
Layflat walls are thin, leaving little cushion under the wire. Use smooth, rounded wire and modest torque; on higher pressure discharge a T-bolt band spreads load over a wider strip of wall.
Four worked examples from the pump yard
Readings marked illustrative are typical values for working the method, not measurements of a specific product.
Example 1: 2 in trash pump suction hose
A contractor’s 2 in trash pump runs heavy duty PVC helix suction hose onto a 2 in hose shank on the camlock tail. A heavy duty hose of this size can be listed around 2.60 in OD (66 mm) before fitting. On the shank, the crest reading comes out at 68 mm, valley 65 mm (illustrative).
- Size to: 68 mm crest.
- Double wire choice: a 65 to 70 mm clamp puts 68 mm in the upper half, leaving about 3 mm of take-up. A 68 to 73 mm clamp would put the reading at its minimum, with no take-up at all. Reject it.
- Count: one clamp is common on 2 in suction, but trash pumps shake. A second clamp a short distance behind the first is cheap insurance.
- OneTouch alternative: the 4ST250H HD spring-loaded T-bolt covers 2.50 to 2.81 in (64 to 71 mm) with a 3/4 in 301 stainless band and a 150 in-lb rating. The spring holds load as PVC relaxes on a vibrating pump; at 69 mm or more, compare the 4ST269H (2.69 to 3.00 in).
Example 2: 3 in irrigation PVC suction
A farm irrigation pump draws from a canal through 3 in PVC liquid suction hose. Published OD for a hose like this sits around 3.62 to 3.64 in (about 92 mm). On the steel shank, the crest reads 94 mm and the valley 91 mm (illustrative).
- Size to: 94 mm crest.
- Double wire choice: a 90 to 95 mm or 92 to 97 mm clamp works. The 90 to 95 mm size gives a tighter final grip; the 92 to 97 mm size is easier to slip on over a flared shank. Either way, pick a heavier wire at this diameter.
- Count: two clamps. This is suction on 3 in hose; an air leak at the shank will cost prime.
- OneTouch alternative: the 4SCH412 hi-torque stainless clamp covers 3.25 to 4.13 in (83 to 105 mm) with a 5/8 in 301 stainless band, 410 stainless screw and 150 in-lb rating.
Example 3: 4 in slurry hose
A dewatering crew runs 4 in rubber slurry hose with a thick wall and steel helix on a submersible slurry pump. There is no point guessing an OD from nominal size; a heavy rubber slurry hose can run well over the 4.76 in published for 4 in PVC helix hose. On the shank, the crest reads 132 mm (illustrative).
- Size to: 132 mm.
- Double wire choice: at this size, screw-type double wire clamps with thin wire struggle. Look for a twin ring bolt clamp with heavy wire (the McMaster-Carr listing moves to 5/16 in wire above about 3-27/32 in) and a range of roughly 128 to 136 mm.
- Count: two, staggered so the bolts are not in line.
- OneTouch alternative: the 4SCH562 hi-torque stainless clamp covers 4.75 to 5.63 in (121 to 143 mm). If your hose measures smaller, the 4SCH512 covers 4.25 to 5.13 in. Both are listed in our hi-torque clamp category.
Example 4: 1-1/2 in pool hose
A pool service company clamps 1-1/2 in corrugated vacuum and backwash hose onto pump and filter adapters. The hose is soft, the pressure is low, and the clamp sees chlorinated water. On the adapter, the crest reads 46 mm (illustrative).
- Size to: 46 mm crest.
- Double wire choice: a 44 to 48 mm stainless double wire clamp, or the inch step that brackets 1.81 in. Snug only; corrugated hose folds if you crank it.
- Count: one.
- OneTouch alternative: the 4TB0175 T-bolt (1.75 to 2.00 in, 44 to 51 mm) is overkill for pool hose, so most crews would use a 4SS worm gear such as the 4SS0032 (1.56 to 2.50 in). Our 4SS clamps use 301 stainless band and housing with a 410 screw, not 316, so rinse them during service on chlorinated equipment. For the grade question in detail, see 304 vs 316 double wire hose clamps.
When your reading lands between two sizes
Double wire ranges are short and often overlap by a millimetre or two, or leave small gaps. Use these rules in order.
- Re-measure. A between-sizes reading is often a measurement taken off the shank or in a valley. Measure again on the crest over the fitting.
- Prefer the size that puts your reading in its upper half. The screw on a double wire clamp pulls the wire ends together; it needs free travel to keep pulling as rubber and PVC creep. A reading near the bottom of a range means the clamp is almost closed before it starts working.
- Never pick a size whose maximum is below your reading. Forcing a clamp open over a hose that is too big distorts the wire loops and the bridge, and it will not seat evenly.
- On soft or corrugated hose, size down within reason. Soft walls compress more, so a slightly smaller range still closes properly. On rigid helix hose, do the opposite: give yourself room to get over the ribs.
- If the gap is genuine, change family. When no double wire size fits well, a wide-range clamp solves it. That is where worm gear and hi-torque clamps earn their keep: our standard 4SS worm gear range steps in overlapping 1/2 in to 1 in spans, and the hi-torque sizes overlap so a reading always falls well inside one part.
Choosing wire gauge for the hose and duty
Wire size matters as much as range on pump hose, and across the makers charted above it grows with diameter: Rotor Clip steps from 0.039 in to 0.078 in, EFC holds two 12 gauge wires to 2.56 in, and twin ring clamps move from 3/16 in to 5/16 in wire.
| Hose and duty | Wire direction | Why |
|---|---|---|
| Soft PVC or corrugated hose, low pressure | Lighter, smooth wire | Heavy wire bites into a soft wall and can cut it as the hose flexes. |
| Rigid PVC helix suction, 2 to 4 in | Medium to heavy wire | The wire must bridge or flatten crests without bending; thin wire deflects between ribs. |
| Rubber slurry or mining hose, 4 in and up | Heaviest wire, bolt drive | Thick walls need high clamping force; screw-type clamps with thin wire cannot deliver it. |
| Layflat on a shank | Smooth, rounded wire, moderate size | Thin fabric wall has no cushion; sharp or heavy wire concentrates load on a narrow line. |
Material follows the same logic as any clamp. Zinc-plated W1 steel is the cheap default and rusts on wet pump yards; McMaster-Carr warns that the steel bolt on its twin ring clamps will rust quickly in wet conditions. Stainless double wire clamps cost more but last on irrigation, dewatering and marine pumps. Our explainer on what a double wire hose clamp is covers the construction, and the guide on how to choose a double wire hose clamp walks through material and screw options.
Swapping a double wire clamp for a OneTouch part
When does a different family do the job as well or better?
- Vibrating pumps, PVC helix hose, 1-1/4 to 3 in: a spring-loaded T-bolt clamp. Browse the T-bolt clamp range (plain 4TB, spring 4ST and HD spring 4ST…H).
- Large suction and slurry hose, 3 to 9 in: hi-torque stainless clamps.
- Light duty pool and garden hose: 4SS all-stainless worm gear clamps.
- Short shanks needing a narrow seal: stay with double wire from a maker that publishes wire and screw size.
For a hose-by-hose view of which clamp families suit suction and discharge work, see best hose clamps for suction and discharge hoses.
Double wire sizing questions from the pump yard
Can I order a double wire clamp by nominal hose size, such as “2 inch”?
Not reliably. Nominal size is the inside diameter. Published outside diameters for 2 in suction hose from one maker alone range from 2.32 in to 2.60 in, a spread bigger than one double wire clamp’s range. Order by measured outside diameter in mm or inches.
Should I measure helix hose over the rib or between ribs?
Over the rib (the crest), with the hose fitted on its shank. Note the between-rib reading as well, because a large gap warns of a possible leak path under the wires on suction service.
Why does my clamp bottom out before the hose seals?
Usually because the clamp range is too small for the hose on its shank, or it was sized from the valley. The wire ends meet before enough force reaches the hose. Go up one size so your crest reading sits in the upper half of the range.
How many double wire clamps go on a suction hose?
One on small hose. From about 3 in upward, two is the safer default on suction lines. Keep both on the shank with screws turned apart.
Are spring double wire clamps the same as screw double wire clamps?
No. Spring types such as Rotor Clip DW are opened with pliers and sized in very narrow steps for small hose; screw types are tightened and used on pump hose. Their charts are not interchangeable.
Does OneTouch Exim sell double wire hose clamps?
No. We supply T-bolt, spring T-bolt, hi-torque, constant torque, worm gear, lined and V-band clamps. Send us your measured hose OD or the double wire part number you use now, and we will suggest the closest family and size from our range.
Send us your crest reading
If you have filled in the field card and want a second opinion, send the crest and valley readings, the hose make and the pump service to us through the OneTouch Exim contact page. If you are replacing a known part number, start with the cross-reference index and we will quote the T-bolt, hi-torque or 4SS size that fits your measurement.