Isolation valves for high-pressure hydraulic lines: one quarter turn between fully open and fully shut, with no meaningful pressure drop when open. Four series cover DN4 to DN50 — the rating falls as the bore grows, so size and pressure have to be read together.
State system pressure, size/thread, fluid & temperature — quotes back within 2 working hours.
| Pattern | Two-way · full bore · quarter turn |
|---|---|
| Series | BKH · BKHP420 · MKHP420 · 3KH |
| Bore | DN4–DN50 — 1/8″ to 2″ thread |
| Pressure | 250–500 bar — depending on size |
| Body | Steel or stainless SS316 |
| Temperature | Steel −20…+100 °C · SS316 −30…+100 °C |
| Ends | BSPP · NPT · DIN 2353 · SAE J514 · welding |
Pressure, dimension and weight tables per part number are on this page, as printed in the catalogue.
| At a glance | BKH | BKHP420 | MKHP420 | 3KH |
|---|---|---|---|---|
| Bore | DN4–25 | DN20–25 | DN32–50 | Small |
| Pressure | 250–500 | 420 flat | 420 flat | 500 @DN6 |
| Body | Hex | Heavy hex | Round | Square |
| Mounting | On pipe | On pipe | On pipe | To plate |
The rating falls as the bore grows, because end load rises with area. Both tables below are BSPP ends; steel and SS316 are not the same.
Steel body, female BSPP
| Type | Bore (mm) | Thread | PN (bar) |
|---|---|---|---|
| BKH-DN4 | 5 | G1/8 | 500 |
| BKH-DN6 | 6 | G1/4 | 500 |
| BKH-DN10 | 10 | G3/8 | 500 |
| BKH-DN13 | 13 | G1/2 | 500 |
| BKH-DN16 | 15 | G5/8 | 420 |
| BKH-DN20 | 20 | G3/4 | 420 |
| BKH-DN25 | 25 | G1 | 315 |
| BKHP420-DN25 | 25 | G1 | 420 |
| BKH-DN25/32 | 25 | G1¼ | 315 |
| BKH-DN25/40 | 25 | G1½ | 315 |
| MKHP420-DN32 | 32 | G1¼ | 420 |
| MKHP420-DN40 | 38 | G1½ | 420 |
| MKHP420-DN50 | 48 | G2 | 420 |
Stainless SS316 body, female BSPP
| Type | Bore (mm) | Thread | PN (bar) |
|---|---|---|---|
| BKH-DN4 | 5 | G1/8 | 500 |
| BKH-DN6 | 6 | G1/4 | 500 |
| BKH-DN10 | 10 | G3/8 | 500 |
| BKH-DN13 | 13 | G1/2 | 500 |
| BKH-DN16 | 15 | G5/8 | 400 |
| BKH-DN20 | 20 | G3/4 | 315 |
| BKHP420-DN20 | 20 | G3/4 | 420 |
| BKH-DN25 | 25 | G1 | 315 |
| BKHP420-DN25 | 25 | G1 | 420 |
| BKH-DN25/32 | 25 | G1¼ | 315 |
| BKH-DN25/40 | 25 | G1½ | 250 |
⚠ Stainless derates further, it is not the same. At G5/8 steel 420 bar against SS316 400 bar; at G3/4 steel 420 bar against standard SS316 315 bar (only BKHP420 lifts it to 420); at G1½ steel 315 bar against SS316 250 bar. If your specification quotes the steel figure but the material is stainless, talk to us before the PO.
Steel, female BSPP
| Part number | Length L (mm) | Weight (kg) |
|---|---|---|
| BKH-DN4-G1/8 | 69 | 0.41 |
| BKH-DN6-G1/4 | 69 | 0.40 |
| BKH-DN10-G3/8 | 72 | 0.54 |
| BKH-DN13-G1/2 | 83 | 0.65 |
| BKH-DN16-G5/8 | 83 | 0.70 |
| BKH-DN20-G3/4 | 95 | 1.50 |
| BKH-DN25-G1 | 113 | 2.20 |
| BKHP420-DN25-G1 | 113 | 3.10 |
| MKHP420-DN32-G1¼ | 111 | 3.47 |
| MKHP420-DN40-G1½ | 130 | 5.67 |
| MKHP420-DN50-G2 | 140 | 8.14 |
Steel, female NPT (ANSI B1.20.1)
| Part number | Bore | Thread | L (mm) | Weight (kg) | PN |
|---|---|---|---|---|---|
| BKH-DN4-1/8″NPT | 5 | 1/8″ | 69 | 0.30 | 500 |
| BKH-DN6-1/4″NPT | 6 | 1/4″ | 69 | 0.40 | 500 |
| BKH-DN10-3/8″NPT | 10 | 3/8″ | 72 | 0.55 | 500 |
| BKH-DN13-1/2″NPT | 13 | 1/2″ | 83 | 0.75 | 500 |
| BKH-DN20-3/4″NPT | 20 | 3/4″ | 95 | 1.63 | 420 |
| BKH-DN25-1″NPT | 25 | 1″ | 113 | 2.30 | 315 |
| BKHP420-DN25-1″NPT | 25 | 1″ | 113 | 3.16 | 420 |
| BKH-DN25/32-1¼″NPT | 25 | 1¼″ | 120 | 2.51 | 315 |
| BKH-DN25/40-1½″NPT | 25 | 1½″ | 130 | 2.70 | 250 |
| MKHP420-DN32-1¼″NPT | 32 | 1¼″ | 120 | 3.52 | 420 |
| MKHP420-DN40-1½″NPT | 38 | 1½″ | 130 | 5.69 | 420 |
| MKHP420-DN50-2″NPT | 48 | 2″ | 140 | 8.14 | 420 |
Steel, DIN 2353 / ISO 8434-1 compression — light series
| Part number | Bore | Thread | L (mm) | Weight (kg) | PN |
|---|---|---|---|---|---|
| BKH-DN4-6L | 5 | M12×1.5 | 67 | 0.36 | 500 |
| BKH-DN6-8L | 6 | M14×1.5 | 67 | 0.37 | 500 |
| BKH-DN8-10L | 8 | M16×1.5 | 74 | 0.38 | 500 |
| BKH-DN10-12L | 10 | M18×1.5 | 74 | 0.50 | 500 |
| BKH-DN13-15L | 13 | M22×1.5 | 82 | 0.61 | 500 |
| BKH-DN13-18L | 13 | M26×1.5 | 82 | 0.60 | 500 |
| BKH-DN16-18L | 15 | M26×1.5 | 82 | 0.75 | 420 |
| BKH-DN20-22L | 20 | M30×2 | 101 | 1.49 | 420 |
| BKH-DN25-28L | 25 | M36×2 | 108 | 2.00 | 315 |
| BKH-DN25/32-35L | 25 | M45×2 | 112 | 2.12 | 315 |
| BKH-DN25/40-42L | 25 | M52×2 | 112 | 2.27 | 315 |
| MKHP420-DN32-35L | 32 | M45×2 | 136 | 3.58 | 420 |
| MKHP420-DN40-42L | 38 | M52×2 | 147 | 5.54 | 420 |
Full dimensions (hex width, lever height, 3KH mounting-hole pitch) are in the MHA catalogues below, as printed. The MHA Zentgraf range continues above the stocked series — to 700 bar and sizes to 4″ — on request.
| System pressure | ≤1/2″ | 3/4″ | 1″ | ≥1¼″ |
|---|---|---|---|---|
| Up to 250 bar | Any BKH | Any BKH | Any BKH | BKH or MKHP420 |
| Up to 315 bar | BKH | BKH | BKH (limit) | BKH (BSPP) or MKHP420 |
| Up to 420 bar | BKH | BKH | BKHP420 | MKHP420 |
| Up to 500 bar | BKH or 3KH | Not available | Not available | Not available |
| Above 500 bar | Outside the catalogue range — talk to us | |||
Series comparison
| Feature | BKH | BKHP420 | MKHP420 | 3KH |
|---|---|---|---|---|
| Bore range | DN4–DN25 | DN20 & DN25 | DN32–DN50 | Small bores |
| Thread range | 1/8″–1½″ | 3/4″ & 1″ | 1¼″–2″ | 1/4″ upward |
| Rating | 250–500 bar (falls with bore) | 420 bar fixed | 420 bar fixed | 500 bar (DN6) |
| Body shape | Hex-flatted | Hex, heavier | Round | Square, mounting holes |
| Mounting | On pipework | On pipework | On pipework | Bolted to plate/manifold |
| Typical weight | 0.30–2.60 kg | 3.10–3.94 kg | 3.47–8.14 kg | Light |
One code fixes the material of every wetted part separately: digit 1 body & adapters, digit 2 ball & stem, digit 3 ball seat, digit 4 sealing on stem & adapters. Name your fluid and we write the code into the quote.
| Code | Body | Ball & stem | Used for |
|---|---|---|---|
| 112A | Steel | Steel | General hydraulics on mineral oil — the default |
| 212A | Steel | Alternative | Duty needing a different ball/stem material |
| 192A | Steel | Steel | Alternative seat — a specific fluid or temperature |
| 442A | Stainless | Stainless | Corrosive, washdown, marine — remember the derate |
| 44HA / 44aA | Stainless | Stainless | Gas duty only — gas seat; never substitute a liquid code |
Fluid → code
| Medium | Typical code | Notes |
|---|---|---|
| Mineral hydraulic oil | 112A | Default — no special requirement |
| Seawater, washdown, salt air | 442A | Remember the SS316 derate: less pressure at the same bore |
| Gas | 44HA / 44aA | Gas duty needs a different seat — never a liquid-service code |
| Water glycol, HFC, fire-resistant fluids | Confirmed per model | Seat and seal matched to the fluid — state it by name |
| Chemical / petrochemical | Confirmed per model | Medium, concentration and temperature all affect the code |
Working temperature
| Body material | Minimum | Maximum |
|---|---|---|
| Steel | −20 °C | +100 °C |
| SS316 | −30 °C | +100 °C |
| End | Standard | What it does |
|---|---|---|
| Female BSPP | DIN ISO 228 | Parallel thread — seals on a bonded washer or O-ring at the port, not on the thread |
| Female NPT | ANSI B1.20.1 | Tapered thread — seals on the thread itself |
| Compression | DIN 2353 / ISO 8434-1 | Straight onto hydraulic tube via a cutting ring — light series 6L–42L |
| SAE | SAE J514 | SAE porting — MKHP420 range only |
| Welding | — | Permanent joint — keep welding heat away from the seals |
BSPP or NPT? BSPP is parallel and needs a sealing face at the port; NPT is tapered and seals on the thread. They are not interchangeable — state which on the PO, not just the inch size.
Takes a padlock — the valve cannot be moved without the key. For lock-out isolation.
Holds the lever positively at open and shut — resists vibration creep. Float and self-cancelling types.
Pneumatic or electric for remote operation — state medium, temperature and pressure so it is sized right.
Reports valve position (open/shut) back to the control panel.
⚠ Do not use it to regulate flow. This is an isolation device: open or shut. Held part-open, the flow is forced through a narrow crescent between ball and seat and the velocity wire-draws the seat — damage that cannot be repaired in the field. For regulation use a needle valve.
Pressure, size, material and fluid — before the valve leaves the box.
Install only on an unpressurised system.
Debris carried through the seat will score it.
No pull or vibration loading the valve body.
Conducted heat ruins the stem sealing.
Full open, full shut — and do not re-torque afterwards.
Flammable or explosive media must be out before work starts.
Dimensions and part numbers are in the catalogues, as printed; stock and price are not — send the list and we confirm both.
Power packs, presses, heavy plant — isolating a line at full working pressure.
SS316 bodies with the material code matched to the fluid.
442A for seawater, washdown and salt air.
Pressurised lines that get isolated often.
High vibration — specify a detent so the lever position cannot creep.
DIN 2353 compression ends straight onto hydraulic tube.
Only with the gas codes 44HA or 44aA — the seat is different.
Where we do not recommend them: food, beverage and pharmaceutical plant — the cavity around the ball cannot be cleaned thoroughly enough for hygienic process.
No — and this is the commonest way these valves get ruined. A ball valve is an isolation device: open or shut. Held part-open, the flow is forced through a narrow crescent between the ball and the seat, and the velocity there wire-draws the seat. Use a needle valve for regulation.
Between 250 and 500 bar depending on the size — the rating falls as the bore grows. BKH-DN4 to DN13 = 500 bar; DN16 and DN20 = 420 bar; DN25 = 315 bar, or 420 bar on the BKHP420.
No — stainless derates further. At G5/8 steel 420 bar, SS316 400. At G3/4 steel 420 bar, standard SS316 315. At G1½ steel 315 bar, SS316 250.
It fixes the material of each wetted part separately: digit 1 body and adapters, digit 2 ball and stem, digit 3 ball seat, digit 4 sealing on the stem and adapters. 112A = steel for mineral oil, 442A = stainless, 44HA/44aA = gas duty.
The reinforced version at the same bore and thread. A BKH-DN25-G1 is rated 315 bar; a BKHP420-DN25-G1 is rated 420 bar — and heavier for it, 3.10 kg against 2.20.
Bore, mostly. BKH: DN4–DN25 (1/8″–1½″ thread). MKHP420: large bores DN32–DN50 (G1¼–G2) at a flat 420 bar. 3KH: square body whose flat sides carry mounting holes for bolting to a plate or manifold rather than into pipework.
Female BSPP (DIN ISO 228), female NPT (ANSI B1.20.1), DIN 2353 / ISO 8434-1 compression straight onto hydraulic tube (light series 6L–42L), SAE J514 on the MKHP420 range, and a welding end.
Steel bodies −20 °C to +100 °C; SS316 bodies −30 °C to +100 °C on the standard material combinations.
Read the body. It carries the type and size (for example MKHP420-DN32-G1 1/4), the pressure (PN420), the material code (442A), the origin and date (GERMANY 33/16) and a works order number. Send a photo on WhatsApp.
Yes — all in place of the plain lever. A locking device takes a padlock; a detent holds the position positively against vibration; an actuator operates it remotely; a limit switch reports the position to a panel.
We do not recommend it. The cavity around the ball cannot be cleaned thoroughly. This range is for hydraulics, chemical, petrochemical, offshore, water, mining, agricultural machinery and gas pipelines.
Yes — the MHA Zentgraf range continues above the series we stock, to 700 bar and sizes to 4″, on request. The tables here are the stocked series, as printed in the catalogue.
Yes — we hold this range in our regional warehouses in Singapore and Malaysia, out within 24 hours of your PO; quotes back within 2 working hours.
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