HYDAC 0660 D 010 ON Filter Element: Model Codes and Replacement

The HYDAC 0660 D 010 ON is a pressure-line filter element installed inside a filter housing. It captures particulate contamination in hydraulic oil to protect downstream valves and actuators.

Matching dimensions alone can still leave a replacement with frequent alarms or inadequate filtration. The following explains the model code, 10 μm filtration rating and 20 bar collapse rating, and how these specifications affect service.

0660 D 010 ON Model Code Breakdown

0660 is a size designation. It does not directly specify element length or a universally permitted flow rate. Filter selection also depends on the housing, actual flow, fluid viscosity and pressure drop.

In the model-code documentation, V denotes a fluorocarbon elastomer seal, while SFREE identifies a design intended to minimise electrostatic charge generation. The current entry for the base model lists Stat-Free as No. The base version should therefore not be specified with the features of the SFREE variant.

Dimensions, Media and Differential-Pressure Strength

When comparing an existing element, check the 91 mm outside diameter, 330 mm length and 48 mm inside diameter separately. These are catalogue dimensions, not fitting tolerances. Measurements from a collapsed element or damaged end cap may also be misleading.

Then check where the open-end O-ring seats and how the end cap locates in the housing. An element can fit inside the housing while an incorrectly seated seal allows oil to bypass the media. Dimensions help narrow the choice; the original housing's replacement-parts information establishes the required fit.

The temperature range must also be considered across the complete assembly. The element, seals, fluid and housing each have limits. The usable range depends on their combination.

How Much Can Two 10 μm Elements Differ?

For two elements labelled 10 μm, the beta ratio is an essential comparison. Under specified test conditions, β is the ratio of upstream to downstream particle counts at or above the stated particle size. A higher beta ratio means a smaller proportion passes through at that size.

At β=1000, efficiency is (1−1/1000) × 100%, or 99.9%. For an illustrative upstream count of 10,000 particles at or above the specified size, the ratio corresponds to approximately 10 downstream particles. This explains the calculation; it is not a machine test record.

Now assume another element has β=200 at the same particle size and under the same test conditions. Its efficiency is 99.5%, corresponding to approximately 50 downstream particles from the same upstream count. That is five times the count at β=1000, although the efficiencies differ by only 0.4 percentage points.

This is an arithmetic comparison of two beta ratios, not a test result for an alternative brand. A purchasing specification should state the filtration rating and the corresponding beta requirement. Data from different test conditions should not be compared directly.

Filtration efficiency alone does not establish service life. Contamination loading, dirt-holding capacity, flow and changes in differential pressure also affect how long an element remains in service.

Why Is the Element Rated at 20 bar in a 200 bar System?

The 20 bar collapse rating describes the element's ability to withstand differential pressure across its structure. The filter housing's allowable system pressure is a separate specification.

For an illustrative gauge reading, assume the filter inlet is at 200 bar and the outlet at 198 bar. Total filter differential pressure is 2 bar. If the inlet remains at 200 bar while the outlet falls to 180 bar, the differential becomes 20 bar. These assumed readings explain the distinction between system pressure and differential pressure.

Gauges across the filter assembly measure total pressure drop, including housing losses. The element's own differential pressure depends on the measurement points and assembly design. Its 20 bar collapse rating is a structural limit, not a continuous operating differential, replacement alarm setting or bypass setting.

A replacement must meet the original assembly's collapse requirements. Check housing pressure, clogging-indicator settings and bypass configuration as well. Bypass cracking pressures listed for return-line elements apply to the corresponding return-line versions and should not be assigned to this D-type pressure element.

A New Element Triggers an Alarm: What to Check

The 0660 designation does not provide a flow guarantee valid for every operating condition. Selection requires the pressure drop of the complete filter at the actual flow and viscosity, including both housing and element losses.

Higher viscosity during a cold start can produce greater differential pressure at the same flow. If an alarm remains after element replacement, record cold and warm oil temperatures and the corresponding differential pressures, then compare actual flow with the original filter requirements. The alarm alone does not establish that the new element is clogged.

An alarm at cold start disappears as the oil warms

Assume the same machine movement produces 0.8 bar total filter differential pressure at normal oil temperature and 3.2 bar during a cold start. If the existing indicator is set to 3 bar, these readings explain an alarm when cold that clears when warm. The 3 bar setting is assumed for this example; it is not a built-in alarm setting of the 0660 D 010 ON element.

Check cold-oil viscosity, startup flow and the filter pressure-drop curves. If differential pressure also keeps rising from the initial 0.8 bar at the same warm temperature and flow, investigate contamination loading, model and installation. One cold-start alarm alone does not establish that the new element is clogged.

If changing 010 to 005, review that variant's pressure drop at the actual flow and viscosity. A finer rating must fit the equipment's cleanliness requirements, supply conditions and available alarm margin.

Keep ON, V and SFREE in the Order

Existing equipment may carry BN4HC, ON or other media designations. Product naming has changed across regions and catalogue editions. Establish the replacement using the original part number, complete code and the manufacturer's replacement records.

0660 D 010 ON and versions with V, SFREE or special-fluid suffixes must be identified separately when ordering. Matching 0660, D and 010 does not resolve differences in seals, electrostatic design or fluid compatibility.

Model and Specifications on the Purchase Order

When ordering 0660 D 010 ON, state the complete model, part number and main specifications so the supplier can quote and supply the same specification:

0660 D 010 ON / 1250495; 10 μm; βx(c)≥1000 and 99.9% efficiency as listed in the current entry; NBR seals; 20 bar collapse rating; 91 mm outside diameter, 330 mm length and 48 mm inside diameter; no SFREE configuration.

Add the housing model, full original element marking, fluid grade, operating temperature and actual flow. If a supplier offers a V version, clarify the seal difference. If another media is proposed, obtain its filtration performance and assembly compatibility information.

The Optimicron documentation classifies these elements as disposable, single-use products. A clean appearance after washing does not establish restored filtration performance or structural integrity. Replace the element according to the maintenance requirements.

For a 0660 D 010 ON replacement, matching dimensions is the starting point for fit. Beta ratio describes particle passage, collapse rating describes differential-pressure strength, and seals and suffixes identify fluid compatibility and special features. Keep the full model when ordering and record initial differential pressure at a known temperature and flow for later maintenance comparisons.