{"id":6245,"date":"2026-10-13T03:03:38","date_gmt":"2026-10-13T03:03:38","guid":{"rendered":"https:\/\/www.henghuahose.com\/?p=6245"},"modified":"2026-10-13T03:03:41","modified_gmt":"2026-10-13T03:03:41","slug":"caustic-alkali-hose-naoh-koh-selection","status":"publish","type":"post","link":"https:\/\/www.henghuahose.com\/ru\/caustic-alkali-hose-naoh-koh-selection\/","title":{"rendered":"Caustic Hose Selection for NaOH and KOH Service"},"content":{"rendered":"

In practice the answer is a compound choice: EPDM (ethylene propylene diene monomer) for dilute caustic and hot water, and a polyolefin or fluoropolymer tube for stronger, hotter or higher-purity duty. A caustic hose for sodium hydroxide or potassium hydroxide service must hold a strongly alkaline liquid, survive the heat it is usually handled at, and flush clean before the alkali crystallizes. Those three demands point to a different material set than the oil-resistant compounds most plants keep on the shelf. Alkali service is where the ordinary rules change, so this guide explains the variables that actually decide the hose.<\/p>\n\n\n\n

1. The Short Answer: Matching a Caustic Hose to NaOH and KOH<\/h2>\n\n\n\n

For most dilute alkaline and hot-water duties, an EPDM tube is the normal starting point. HENGHUA publishes a program of chemical hose<\/a> for these duties, and publishes EPDM as its compound for hot water, steam up to +165 \u00b0C, brake fluid and dilute acids. The same call-out states plainly that EPDM is not for oils.<\/p>\n\n\n\n

That is why alkali service is not a plain job for the oil-resistant compounds a plant may already stock. Where concentration, temperature or purity push past what EPDM is published to cover, polyolefin tubes such as UHMWPE, XLPE or polypropylene, and fluoropolymer tubes such as PTFE (polytetrafluoroethylene), FEP or PFA, become the options to compare.<\/p>\n\n\n\n

Table 1. Compound options for caustic and alkali hose service<\/p>\n\n\n\n

Compound<\/th>Coverage cited in this article<\/th>Role in NaOH and KOH service<\/th><\/tr><\/thead>
EPDM<\/td>Hot water, steam up to +165 \u00b0C, brake fluid and dilute acids (HENGHUA published call-out)<\/td>Normal starting point for dilute alkaline and hot-water duty; not for oils<\/td><\/tr>
NBR<\/td>Mineral oils, diesel and hydraulic fluids (HENGHUA published call-out)<\/td>Oil-service compound; not the default for alkaline media<\/td><\/tr>
FKM (fluorocarbon)<\/td>High-temperature oils and aggressive chemicals up to +200 \u00b0C (HENGHUA published call-out)<\/td>For high temperature combined with aggressive chemical exposure<\/td><\/tr>
PTFE<\/td>Nearly all chemicals, \u221270 \u00b0C to +260 \u00b0C (HENGHUA published call-out)<\/td>Fluoropolymer option at the demanding end of alkali duty<\/td><\/tr>
Polyolefins: UHMWPE, XLPE, polypropylene<\/td>Generic compound family; no single per-product rating is claimed here<\/td>Considered with fluoropolymers where concentration, temperature or purity demand more<\/td><\/tr>
Fluoropolymers: FEP, PFA<\/td>Generic compound family; no single per-product rating is claimed here<\/td>Same role as PTFE where the service demands it<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Two questions decide most alkali jobs. The first is whether the tube’s published coverage reaches your working temperature, not just your medium. The second is whether the hose can be flushed clean after the run. Answer both before you compare prices, because a cheaper tube that is not cleanable will cost more over a year of blocked lines and premature replacement.<\/p>\n\n\n\n

2. Why Caustic Is Not Just Another Chemical<\/h2>\n\n\n\n

NaOH and KOH are both strongly alkaline, and that alone separates them from the acids and solvents handled elsewhere on site. Alkali attack on a polymer is not the same failure mode as acid attack, and a compound that performs well against one family tells you nothing about the other. Two practical habits follow. First, caustic is usually handled hot, so the hose sees a hot concentrated liquid rather than a cool dilute one. Second, the same alkali hangs up as a solid when it cools, so a hose that is not flushed can set hard inside.<\/p>\n\n\n\n

That combination \u2014 hot, concentrated, and prone to solidifying on cooling \u2014 is what makes alkali service different for a caustic hose. A hose that survives the chemistry but cannot be cleaned will still fail, because the residue is the problem. A hose that is cleanable but softens at the working temperature will also fail. Selection therefore has to cover the tube compound, the temperature envelope and the cleaning routine together, and not one at a time.<\/p>\n\n\n\n

Temperature is what tips the balance in most plants. A dilute alkali at ambient temperature is a far easier proposition than the same alkali concentrated and hot, and the two do not call for the same tube or the same end connection. The hose is often the last item on the line to be reviewed, even though it is the item that has to flex, bend and be replaced by hand.<\/p>\n\n\n\n

A sodium hydroxide hose is not simply a potassium hydroxide hose with a different label. The two alkalis are handled at different strengths and see different cooling behavior on the same site, so the same physical layout can need two different tube compounds. Check the medium on the line before you reuse a specification from a neighboring unit.<\/p>\n\n\n\n

What the hose has to do:<\/h3>\n\n\n\n