Hydrostatic head is a measure used to point the waterproofness of a material, particularly for out of doors gear and clothes similar to tents, jackets, and tarps. It signifies the utmost water stress a material can stand up to earlier than it begins to leak. The upper the hydrostatic head worth, the extra waterproof the fabric.
How Is Hydrostatic Head Measured?
To check hydrostatic head, a pattern of material is clamped tightly over a sealed tube full of water. The water stage within the tube is progressively elevated, creating stress in opposition to the material. The measurement is recorded on the level when water begins to seep by way of the material. This worth is often given in millimeters (mm), which represents the peak of the water column the material may help earlier than leaking. For instance, a hydrostatic head of three,000 mm means the material can stand up to a column of water 3 meters excessive earlier than water penetrates.
Why Does Hydrostatic Head Matter?
Hydrostatic head is essential for anybody who wants dependable waterproof safety. For tents, a minimal hydrostatic head ranking of about 1,500 mm is usually thought-about mandatory for mild rain. Nevertheless, for heavy rain or lengthy publicity to moist situations, greater rankings (like 3,000 mm or extra) are advisable. For waterproof jackets and trousers, comparable and even greater rankings are required to make sure you keep dry throughout extended dangerous climate.
What Impacts Hydrostatic Head?
A number of components influence a material’s hydrostatic head:
- Material Sort: Tightly woven materials are likely to have greater resistance to water.
- Coatings & Laminates: Supplies like polyurethane (PU) coatings or Gore-Tex membranes considerably improve hydrostatic head by offering extra waterproof limitations.
- Put on and Tear: Over time, abrasion or washing can cut back the effectiveness of waterproof coatings, decreasing the hydrostatic head.
- Seam Sealing: Even when the material itself is extremely waterproof, seams may be weak factors the place water enters except they’re correctly sealed.
Sensible Hydrostatic Head Scores
Right here’s what widespread hydrostatic head rankings imply in sensible phrases:
- 1,000 mm – 1,500 mm: Appropriate for mild showers and brief durations within the rain. Not perfect for sustained moist climate.
- 2,000 mm – 3,000 mm: Good for reasonable rain and longer publicity.
- 5,000 mm and above: Wonderful waterproofing; appropriate for heavy rain and standing water.
Tent Hydrostatic Head Comparability
Listed here are some common light-weight tents that illustrate the vary of “waterproofness” obtainable in the present day.
| Make / Mannequin | Hydrostatic Head |
|---|---|
| Huge Agnes Copper Spur UL2 | 1200mm fly, 1200mm flooring |
| MSR Hubba Hubba LT2 | 1200mm fly, 1200mm flooring |
| NEMO Dagger OSMO 2 | 2000 mm fly, 2000mm flooring |
| Gossamer Gear The Two | 1800mm fly. 3000mm flooring |
| Tarptent Rainbow Silpoly | 3000mm fly, 3000mm flooring |
| Six Moon Designs Lunar Duo | 1500mm fly, 3000mm flooring |
| Lightheart Gear Firefly Silpoly | 3000mm fly, 3000mm flooring |
| Durston X-Mid 2 | 2000mm fly, 5000mm flooring |
| SlingFin Portal 2 | 1800mm fly. 4000mm flooring |
| Hilleberg Anaris | 5000mm fly, 15,000mm flooring |
| Tarptent Arc Dome2 Extremely | 140,000mm+, 5000mm flooring |
| Zpacks Duplex | 20,000+mm fly, 20,000+mm flooring |
| Hyperlite Mtn Gear Crosspeak 2 | 20,000+mm fly, 20,000+mm flooring |
Limitations
Hydrostatic head solely measures resistance to water penetration underneath static stress. In real-world conditions, similar to driving rain or stress from kneeling or sitting on moist floor, precise waterproof efficiency could also be decrease than lab outcomes counsel. Breathability is one other issue; very excessive hydrostatic head values can generally imply much less breathable materials, resulting in condensation inside tents or jackets.
Abstract
Hydrostatic head is an easy technique for evaluating the waterproofness of various materials. It helps customers make knowledgeable selections primarily based on their wants, whether or not that’s light-weight safety for infrequent showers or high-performance gear for harsh climate. All the time take into account each the hydrostatic head ranking and different options, similar to breathability and seam sealing, when selecting waterproof gear.
SectionHiker by no means accepts fee for gear evaluations or editorial protection. While you purchase by way of affiliate hyperlinks on our web site, we could earn a small fee at no additional price to you. Assist us proceed to check and write unsponsored and unbiased gear evaluations, mountaineering and backpacking FAQs, and free mountaineering guides.
