Hydac SK210-10/3218S-210ACM-KCH-15H Piston Accumulator, 10 L

A repairable 10 litre piston accumulator for 3000 psi hydraulics

The Hydac SK210-10/3218S-210ACM-KCH-15H (HYDAC part number 2800007) is a standard-offering model of the SK210 series, an intermediate-bore, repairable piston accumulator for 3000 psi. A piston separates oil and nitrogen, so it suits applications that need high flow rates, a larger usable volume and a higher pressure ratio than a bladder type. This model stores 10 litres (2.5 gallons), with a 150 mm bore, a fluid port of SAE-24 (1 7/8-12 UN) and a 776 mm overall height.

The series is listed by HYDAC for mobile and industrial hydraulics and has a Military Style gas valve, repairable.

Technical specifications

Order code decoded

SK 210 – 10 / 3218 S – 210 ACM – KCH – 15 H: SK210 is the 3000 psi non-ASME series, 10 the size in litres, 3218 the general-duty piston (3), machined carbon steel piston (2), carbon steel cylinder (1) and PUR seals (8), S the USA country code, 210 the working pressure in bar, ACM a female threaded fluid port with the SAE-24 size, KCH the two-piece gas valve with cover, 15 the 150 mm piston diameter and H made in the USA. The KCH gas valve needs a charging kit for precharging, which HYDAC lists as an accessory.

Piston or bladder

Choose a piston accumulator when you need high flow, high pressure ratio or a large usable volume, and have clean fluid. The datasheet gives filtration of 10 micron absolute for piston types, and the PUR seal suits mineral oils and non-flammable HFA fluids but is not resistant to water, alkalis or acids. A bladder is easier on an unfiltered system. Because the SK210 is repairable, seals and piston can be replaced, which suits long service life.

Specify the precharge pressure and the temperature range of your application, and keep the fluid clean, because particles damage piston seals faster than they damage bladders. The datasheet also lists piston position indicators and limit switches as options on larger series if you need to monitor the piston stroke.

The dimensions in the datasheet table show the unit as 150 mm in bore and give a weight of 132 lb, so check the clamp size. The piston type is general duty, and the datasheet gives a maximum piston speed figure for this type, which limits the discharge flow, so ask the supplier to confirm the flow for your application. The two-piece gas valve with protective cover keeps the gas side protected from dirt between checks.

Related Hydac products: Hydac SK280-0.5/3218U-280ACF-VB-05 Piston Accumulator, Hydac SB330TR-10A1/112S1-210A Bladder Accumulator, 10 L, Hydac SBO200-1E1/112S-210AB Diaphragm Accumulator, 1 L, Hydac SB600-10A1/112S-345C Bladder Accumulator, 345 bar, Hydac SB330 Bladder Accumulator and Hydac SK350-10/3218S-210ACM-KCH-18H Piston Accumulator, 10 L.

Documents and quotation

The piston accumulator catalogue section is attached. Please state the precharge, fluid and approval. See also our hydraulic valves and components category.

How the SK210-10/3218S-210ACM-KCH-15H works

A HYDAC piston accumulator consists of a fluid section and a gas section, with a lightweight piston acting as a gas-proof screen between them. The gas side is precharged with dry nitrogen. When system pressure rises above the precharge, oil enters the fluid side, pushes the piston towards the gas end and compresses the nitrogen; when pressure falls, the expanding gas drives the piston back and returns the stored oil to the circuit. Construction is simple: a cylinder with a finely finished internal surface, an end cap on the gas side and another on the fluid side (each sealed with O-rings), the piston and its sealing system. Where more gas volume is needed than the cylinder holds, HYDAC notes that auxiliary gas bottles are frequently used with piston accumulators.

HYDAC lists several advantages of the piston design: high ratios between precharge pressure and maximum working pressure, high flow rates, gas-proof and leak-free operation, space efficiency and no sudden discharge of gas when a seal is worn. That last point is a key safety difference from a failed bladder.

Piston type 3 (general duty)

The first digit of "3218" selects the general-duty type 3 piston. The HYDAC catalogue gives a maximum continuous velocity of 3 ft/sec for this piston and asks for filtration of 10 µm absolute (ISO 17/15/12). If your duty involves very fast, frequent strokes or very small pressure differentials, the catalogue offers the type 2 low-friction piston instead, rated for up to 12 ft/sec continuous with no stick-slip effect.

Seal and material options in the SK210 series

PUR is resistant to mineral oils (HL and HLP) and HFA fluids. If your system runs water-glycol, a fluid with HFD-type chemistry or another special medium, ask for a different seal code, because PUR is not resistant to water and water-glycol mixtures, alkalis or acids.

Selection & ordering guide

• Size: the SK210 standard offering with the 150 mm (6 in) bore, SAE-24 port and KCH valve includes 4, 6, 10, 20, 28 and 40 litre versions (for example SK210-20/3218S-210ACM-KCH-15H). Choose the size from your required usable oil volume, the minimum and maximum system pressure and the precharge.
• Pressure: "210" means a 210 bar (3000 psi) maximum working pressure. For 5000 psi duty, look at the SK350 non-ASME series instead.
• Country code: "S" is the USA designation; S1 (Canada, CRN registered) and U (PED/CE) are other codes in the key, so state the country of installation when you request a quote.
• Monitoring: supplementary equipment such as limit switches and position measuring systems is listed only for the SK350 and SK600 series.

Installation & maintenance

HYDAC piston accumulators may operate in any position, but vertical installation with the gas side up is preferred. HYDAC recommends its own mounting components (clamps and supports) to minimise the risk of failure caused by system vibration. Precharge only with dry nitrogen, never with air or oxygen; the KCH two-piece gas valve requires an FPO charging kit. Check the precharge regularly, ideally at the operating temperature, because gas pressure changes with temperature – an important point in Gulf plant rooms and outdoor skids.

When the SK210-10/3218S-210ACM-KCH-15H is repaired, HYDAC stresses that the correct tools are critical to avoid seal damage: a seal assembly tool to stretch the seals evenly onto the piston, and a piston insertion tool that protects the seals from the shell thread and aligns the piston. Seal kits and complete replacement pistons are available per bore diameter. Only qualified persons should carry out maintenance on any accumulator, and the gas side must be fully discharged first.

Typical applications in Oman & the GCC

• Energy storage to cover peak flow demand in industrial power units and presses
• Emergency and back-up power for valve actuation or braking circuits
• Pulsation and shock damping in mobile hydraulics on construction and port equipment
• Leakage and thermal-expansion compensation in clamping and holding circuits

Why source from Seven Star LLC

Seven Star LLC supplies HYDAC accumulators and hydraulic components across Oman and the GCC. Send us your required volume, pressure range, fluid and country of installation, and our team can help confirm the correct ordering code for the SK210-10/3218S-210ACM-KCH-15H or an alternative size. Request a quote with your project details.