{"id":6247,"date":"2026-10-13T02:59:46","date_gmt":"2026-10-13T02:59:46","guid":{"rendered":"https:\/\/www.henghuahose.com\/?p=6247"},"modified":"2026-10-13T02:59:49","modified_gmt":"2026-10-13T02:59:49","slug":"chemical-suction-discharge-hose-types-pressure-ratings","status":"publish","type":"post","link":"https:\/\/www.henghuahose.com\/es\/chemical-suction-discharge-hose-types-pressure-ratings\/","title":{"rendered":"Chemical Suction and Discharge Hose: Types and Pressure Ratings"},"content":{"rendered":"

A chemical suction and discharge hose is one assembly that has to do two opposite jobs. It holds its shape against vacuum while the pump pulls, and it carries pressurized fluid on the way out. What a hose can do on each side depends on its construction, above all an internal helix or other embedded reinforcement that resists collapse, and on the pressure rating it carries. This guide separates the two duties, then explains the type frames, the pressure vocabulary and the selection steps that decide which hose belongs on your pump.<\/p>\n\n\n\n

Suction and discharge are not interchangeable words. They describe which way the force acts on the hose wall, and that decides the reinforcement, the end connections and the number you must check before the hose enters service. The sections below follow that order: duty, construction, type frame, rating, bore, application. Each one ends where the next begins, so you can read it straight through or jump to the decision you are making today.<\/p>\n\n\n\n

1. Suction Duty and Discharge Duty Load the Wall in Opposite Directions<\/h2>\n\n\n\n

On the discharge side the fluid is already under pressure, so the force pushes outward on the tube and puts the reinforcement in tension. On the suction side the pump creates a partial vacuum, so atmospheric pressure pushes inward on the tube and tries to flatten it. The wall therefore has to resist collapse rather than a hoop load. That is a fundamentally different structural job, and it is the reason the two duties are specified separately on every serious hose datasheet.<\/p>\n\n\n\n

A chemical discharge hose can be built lighter and more flexible than a chemical suction hose of the same bore. Nothing pulls the discharge hose inward, so it needs no helix to keep the bore open. The moment a discharge-only hose is placed on the suction side of a pump, the vacuum has no structural element to work against, and the bore can pinch shut.<\/p>\n\n\n\n

Run a discharge-only hose on suction and the failure tends to arrive early and quietly. The bore flattens at the first restriction, flow drops, and the flexing point concentrates fatigue in a wall that was never reinforced for it. If the medium is hazardous as well, a collapsed suction line can starve the pump and generate the pressure swings the system was never designed to absorb.<\/p>\n\n\n\n

2. What Makes a Chemical Suction and Discharge Hose Different<\/h2>\n\n\n\n

The defining feature of a chemical suction and discharge hose is a structural element built into the wall. It is usually a rigid helix, a wire or polymer spiral wound through the carcass, or an embedded reinforcement layer that performs the same anti-collapse job. The helix carries the inward vacuum load while the tube and cover materials handle the chemical side of the duty.<\/p>\n\n\n\n

Because of that reinforcement, the suction side of the market splits into a few recognizable construction groups. The suction hose types you meet most often in chemical service are the wire-helix rubber hose, the smooth-bore rubber suction and discharge hose, and the thermoplastic composite hose used where a very wide chemical or temperature range is required. Each group protects the bore differently and each is verified differently, so the group is a decision, not a detail.<\/p>\n\n\n\n

The plain-language distinction between a hose that only delivers and a hose that also pulls is worth reviewing before you order. Our suction hose vs delivery hose explainer sets out the construction test in one page. It is a useful sanity check when a quote names a delivery hose for what is clearly a suction line.<\/p>\n\n\n\n

\"Cutaway<\/figure>\n\n\n\n

Figure 1. The internal helix carries the inward vacuum load that a discharge-only hose has no structure to resist.<\/p>\n\n\n\n

HENGHUA builds a 250 psi suction and discharge line<\/a> with the helix bonded through the wall, and a lighter 150 psi version for duty that does not need the higher rating. Both are covered in the rating and application sections below.<\/p>\n\n\n\n

3. The Type Frame: EN 12115:2021 and the Composite Alternative<\/h2>\n\n\n\n

Standards exist so that the words “chemical hose” mean something specific. EN 12115:2021 covers rubber and plastics hose assemblies for chemicals, and it defines two assembly types, D and SD, together with four electrical grades. The type letters carry real meaning for your application, so match them against the pump side before you compare quotes.<\/p>\n\n\n\n

Table 1. Type and grade frame for chemical hose assemblies, quoted from the published standards.<\/p>\n\n\n\n

Reference<\/th>What it defines<\/th><\/tr><\/thead>
EN 12115:2021 assembly types<\/td>Type D and Type SD. The type letter indicates whether the assembly is built for discharge duty alone or for suction and discharge duty, so it is the first item to match against your service.<\/td><\/tr>
EN 12115:2021 service range<\/td>Chemicals in the range \u221220 \u00b0C to +65 \u00b0C at a working pressure \u2264 10 bar.<\/td><\/tr>
EN 12115:2021 electrical grades<\/td>M = electrically bonded; \u03a9 = electrically conductive; M\/T and \u03a9\/T = as above plus through-wall electrical resistance \u2264 10 \u03a9. Electrical testing refers to EN ISO 8031:2020.<\/td><\/tr>
EN 13765:2018 composite hose<\/td>Thermoplastic multi-layer (non-vulcanized) composite hose for hydrocarbons, solvents and chemicals: four types (Type 1 to 4), bores 25 mm to 300 mm, working pressures 4 bar to 14 bar, working temperatures \u221230 \u00b0C to +150 \u00b0C.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Read the service line carefully. EN 12115:2021 is written for \u221220 \u00b0C to +65 \u00b0C at a working pressure of 10 bar or less, and 10 bar converts to about 145 psi (calculated: 10 bar multiplied by 14.50 psi per bar). If your duty sits above that pressure or above that temperature band, the rubber and plastics frame is no longer the natural home for the hose, and you move to the composite frame.<\/p>\n\n\n\n

That is where the composite alternative earns its place. EN 13765:2018 reaches a working pressure of 14 bar, about 203 psi (calculated), and a working temperature of +150 \u00b0C, which is a wider band than the rubber frame on both ends. The trade-off is handling, because a composite hose of the same bore is built differently and often behaves more like a stiff assembly than a flexible rubber line.<\/p>\n\n\n\n

For the assemblies this site supplies, the chemical hose category<\/a> lists both rubber suction and discharge lines and the composite options by bore, rating and material.<\/p>\n\n\n\n

4. Pressure Rating Vocabulary: Working, Test, Burst and Vacuum<\/h2>\n\n\n\n

Pressure numbers get quoted loosely, and a loose quote is how a hose ends up on a line it cannot hold. Four terms matter, and they are not interchangeable. Table 2 sets out what each one covers and, just as important, what it leaves out.<\/p>\n\n\n\n

Table 2. Pressure terms on a hose datasheet and what each one actually covers.<\/p>\n\n\n\n

Term<\/th>What it means<\/th>What it does not tell you<\/th><\/tr><\/thead>
Presi\u00f3n de trabajo<\/td>The maximum pressure the assembly is rated to see in continuous service. HENGHUA publishes the chemical discharge hose at 150 psi and the chemical suction and discharge hose at 150 psi and 250 psi.<\/td>It does not set the vacuum capability and it does not include surge.<\/td><\/tr>
Test or proof pressure<\/td>A one-off pressure applied to prove the assembly holds. Facility tests of nonmetallic transfer hose run at static liquid pressure of at least 1.5 times the maximum allowable working pressure (MAWP) under 33 CFR 156.170(c)(1).<\/td>A pass does not raise the working pressure; it only verifies the assembly on that day.<\/td><\/tr>
Burst pressure<\/td>The pressure at which the assembly fails. Under 33 CFR 154.500(a), the minimum design burst must be at least four times the relief-valve setting pressure, or the maximum pump pressure where no relief valve is fitted, plus the static head pressure of the transfer system at the point where the hose is installed.<\/td>Burst pressure must not be marked on the hose under 33 CFR 154.500(g); record it elsewhere.<\/td><\/tr>
Vacuum rating<\/td>The collapse resistance of a suction assembly, which is a separate number from any pressure rating.<\/td>A pressure rating says nothing about how much vacuum the hose will take.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\"Diagram<\/figure>\n\n\n\n

Figure 2. Working, test and burst pressure sit at clearly different levels; the vacuum rating is not on this scale at all.<\/p>\n\n\n\n

HENGHUA applies a 4:1 design safety factor across the site, which is the same ratio the US transfer-hose rule uses as a floor. The design burst has to be at least four times the pressure the system can present at the hose. If you know the relief-valve setting and the static head at the hose, you can add them, multiply by four, and check whether a candidate rating is honest for your line.<\/p>\n\n\n\n

The published ratings keep this simple on the product pages. There is a 150 psi suction and discharge hose<\/a> for lighter duty and a 250 psi line for a harder pull, plus a 150 psi discharge hose<\/a> where the hose only ever delivers.<\/p>\n\n\n\n

5. Reading a Chemical Suction and Discharge Hose Pressure Rating in Real Service<\/h2>\n\n\n\n

A hose pressure rating is a steady-state figure. Real transfer service is rarely steady, and three effects push a line past the number on the datasheet: surge, static head and temperature. A rating that only covers smooth flow does not describe what the hose sees at the moment a valve closes.<\/p>\n\n\n\n

Surge, often called water hammer, is the transient spike when a valve shuts or a pump starts. It can sit well above the working pressure for a fraction of a second. Static head is the pressure the fluid column adds at the hose whenever the hose sits below the liquid level it is draining. Temperature moves a rating too, because a maker’s derating factor applies to the working pressure, so the derated working pressure equals the rated pressure multiplied by the factor (calculated).<\/p>\n\n\n\n

Vacuum is the fourth input, and it is not on the pressure scale at all. A suction and discharge hose pulls against atmospheric pressure, and the collapse load rises with bore rather than with the discharge rating. Full vacuum is 29.9 inHg, or 1.013 bar, or 760 mmHg, depending on the gauge you read. That is the load a suction line must survive, and no discharge rating describes it.<\/p>\n\n\n\n

Surge, head and temperature also compound one another. A hot medium at the top of its band, draining into a hose that sits below the tank outlet, with a quick-closing valve upstream, presents three simultaneous reasons the effective pressure is above the steady-state figure. The safe habit is to size the hose on the worst plausible combination rather than the average one, and to keep the vacuum figure separate when you write the specification.<\/p>\n\n\n\n

6. Bore Selection for a Chemical Suction and Discharge Hose<\/h2>\n\n\n\n

Bore (the inside diameter, ID) drives two things at once, and they pull in opposite directions. Flow capacity rises sharply with bore, and so do handling weight and stiffness. The arithmetic is simple enough to keep in your head, and it is the fastest way to avoid an over- or under-sized line.<\/p>\n\n\n\n

Table 3. Bore, flow area and friction loss, each relative to a 25 mm bore at the same flow (calculated).<\/p>\n\n\n\n

Bore<\/th>Relative flow area<\/th>Relative friction loss at the same flow<\/th><\/tr><\/thead>
25 mm (about 1 in)<\/td>1.00<\/td>1.00<\/td><\/tr>
50 mm (about 2 in)<\/td>4.00<\/td>0.034<\/td><\/tr>
100 mm (about 4 in)<\/td>16.00<\/td>0.0012<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

The area column follows from the square law: area scales with the square of bore, so doubling the bore gives four times the area (calculated). The friction column follows the Hazen\u2013Williams form, in which friction loss scales with roughly the 4.87 power of diameter (calculated). Moving from a 25 mm bore to a 50 mm bore cuts friction loss to about 3.4 percent of the smaller hose at the same flow, and going to 100 mm cuts it to about 0.1 percent.<\/p>\n\n\n\n

What the table does not show is the other half of the trade. A larger bore means more wall material per meter and a heavier, stiffer assembly, so the hose that moves fluid most easily is also the hose a two-person crew has to carry and bend around a pump skid. The right bore is the smallest one that keeps velocity and pressure drop acceptable, not simply the largest one available.<\/p>\n\n\n\n

If you are sizing from scratch, our hose size selection guide walks through the velocity and pressure-drop checks step by step. When the medium is aggressive, the bore is also bounded by the sizes the material is actually made in. HENGHUA’s published program range is ID 3 mm to 102 mm (1\/8 in to 4 in), which covers the common chemical transfer sizes. For a chemical suction hose the bore also sets the collapse load, which rises with diameter, so the pull side deserves the same arithmetic as the flow side.<\/p>\n\n\n\n

\"Cross-sections<\/figure>\n\n\n\n

Figure 3. Doubling the bore gives four times the flow area, which is why a small change in bore moves capacity so far.<\/p>\n\n\n\n

7. Application Walk-Through: Matching Duty to Service<\/h2>\n\n\n\n

Five services cover most chemical hose questions, and each one settles whether the duty is suction, discharge or both before any material is chosen. Table 4 is the short version of the walk-through, and the paragraph after it gives the decision order.<\/p>\n\n\n\n

Table 4. Common chemical transfer services and the duty each one places on the hose.<\/p>\n\n\n\n

Service<\/th>Deber<\/th>What governs the choice<\/th><\/tr><\/thead>
Tank unloading<\/td>Suction and discharge<\/td>The hose both pulls from the tank and delivers onward, so it needs the helix and a suction and discharge rating.<\/td><\/tr>
Tote and drum transfer<\/td>Suction and discharge<\/td>Short runs, tight bends and frequent handling; bore and flexibility matter as much as the rating.<\/td><\/tr>
Pump discharge<\/td>Discharge only<\/td>No vacuum, so a lighter discharge hose is correct and a suction assembly is unnecessary cost.<\/td><\/tr>
Rail or road tanker<\/td>Discharge, often suction<\/td>Static head and surge dominate; check the 4:1 burst logic against the relief-valve setting.<\/td><\/tr>
Dock transfer<\/td>Discharge<\/td>Long lengths and a flexible assembly; the electrical grade and bonding practice matter on top of the rating.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

The order of decisions is the same in every case. Fix the duty first, because it decides whether a helix is needed at all. Then fix the medium with its concentration and temperature, because they decide the tube compound and whether the rubber frame or the composite frame fits.<\/p>\n\n\n\n

Then fix the bore from velocity and friction, then the rating from the worst-case pressure, and finally the connections and the electrical grade. The suction hose types differ mainly in how they shield the bore, so settle the type for the suction side before you start comparing tube materials.<\/p>\n\n\n\n

For the two ends of the suction and discharge range, the product pages carry the published ratings: a 250 psi suction and discharge hose for harder duty and a 150 psi line for lighter jobs, alongside the discharge-only 150 psi hose. All of them sit inside the chemical hose range this site manufactures.<\/p>\n\n\n\n

8. Specification Checklist<\/h2>\n\n\n\n

Use the list below as the order of questions on the inquiry. Every item maps to a decision made earlier in this article, and a hose ordered without one of them is a hose ordered on an assumption. Take them in this order:<\/p>\n\n\n\n